Removed typing_extensions requirement (#801)

The README has stated that pytube is dependency-free for quite a while, but this isn't entirely true -- the typing_extensions library was added during development of Pytube 3.

Removes typing_extensions dependency used for two type annotations, so pytube can truly be dependency-free.

Pipfile

@@ -4,7 +4,6 @@ verify_ssl = true
 name = "pypi"
 
 [packages]
-typing_extensions = "*"
 
 [dev-packages]
 black = "==19.10b0"

Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "6cc6eccbe11b6084e6d3563f773f9e79d98e383d7c22b35007e65f867a78a554"
+            "sha256": "645f7c4ebe0063c8792c09632043e70611eb74a46dba8d29954a84bb25e0706f"
         },
         "pipfile-spec": 6,
         "requires": {},
@@ -13,17 +13,7 @@
             }
         ]
     },
-    "default": {
-        "typing-extensions": {
-            "hashes": [
-                "sha256:7cb407020f00f7bfc3cb3e7881628838e69d8f3fcab2f64742a5e76b2f841918",
-                "sha256:99d4073b617d30288f569d3f13d2bd7548c3a7e4c8de87db09a9d29bb3a4a60c",
-                "sha256:dafc7639cde7f1b6e1acc0f457842a83e722ccca8eef5270af2d74792619a89f"
-            ],
-            "index": "pypi",
-            "version": "==3.7.4.3"
-        }
-    },
+    "default": {},
     "develop": {
         "alabaster": {
             "hashes": [
@@ -39,18 +29,28 @@
             ],
             "version": "==1.4.4"
         },
+        "atomicwrites": {
+            "hashes": [
+                "sha256:6d1784dea7c0c8d4a5172b6c620f40b6e4cbfdf96d783691f2e1302a7b88e197",
+                "sha256:ae70396ad1a434f9c7046fd2dd196fc04b12f9e91ffb859164193be8b6168a7a"
+            ],
+            "markers": "sys_platform == 'win32'",
+            "version": "==1.4.0"
+        },
         "attrs": {
             "hashes": [
-                "sha256:26b54ddbbb9ee1d34d5d3668dd37d6cf74990ab23c828c2888dccdceee395594",
-                "sha256:fce7fc47dfc976152e82d53ff92fa0407700c21acd20886a13777a0d20e655dc"
+                "sha256:31b2eced602aa8423c2aea9c76a724617ed67cf9513173fd3a4f03e3a929c7e6",
+                "sha256:832aa3cde19744e49938b91fea06d69ecb9e649c93ba974535d08ad92164f700"
             ],
-            "version": "==20.2.0"
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==20.3.0"
         },
         "babel": {
             "hashes": [
                 "sha256:1aac2ae2d0d8ea368fa90906567f5c08463d98ade155c0c4bfedd6a0f7160e38",
                 "sha256:d670ea0b10f8b723672d3a6abeb87b565b244da220d76b4dba1b66269ec152d4"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.8.0"
         },
         "black": {
@@ -73,6 +73,7 @@
                 "sha256:32e43d604bbe7896fe7c248a9c2276447dbef840feb28fe20494f62af110211d",
                 "sha256:cf22deb93d4bcf92f345a5c3cd39d3d41d6340adc60c78bbbd6588c384fda6a1"
             ],
+            "markers": "python_full_version >= '3.6.1'",
             "version": "==3.2.0"
         },
         "chardet": {
@@ -87,16 +88,26 @@
                 "sha256:d2b5255c7c6349bc1bd1e59e08cd12acbbd63ce649f2588755783aa94dfb6b1a",
                 "sha256:dacca89f4bfadd5de3d7489b7c8a566eee0d3676333fbb50030263894c38c0dc"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3, 3.4'",
             "version": "==7.1.2"
         },
         "codecov": {
             "hashes": [
                 "sha256:61bc71b5f58be8000bf9235aa9d0112f8fd3acca00aa02191bb81426d22a8584",
+                "sha256:a333626e6ff882db760ce71a1d84baf80ddff2cd459a3cc49b41fdac47d77ca5",
                 "sha256:d30ad6084501224b1ba699cbf018a340bb9553eb2701301c14133995fdd84f33"
             ],
             "index": "pypi",
             "version": "==2.1.10"
         },
+        "colorama": {
+            "hashes": [
+                "sha256:5941b2b48a20143d2267e95b1c2a7603ce057ee39fd88e7329b0c292aa16869b",
+                "sha256:9f47eda37229f68eee03b24b9748937c7dc3868f906e8ba69fbcbdd3bc5dc3e2"
+            ],
+            "markers": "sys_platform == 'win32' and sys_platform == 'win32'",
+            "version": "==0.4.4"
+        },
         "coverage": {
             "hashes": [
                 "sha256:0203acd33d2298e19b57451ebb0bed0ab0c602e5cf5a818591b4918b1f97d516",
@@ -163,6 +174,7 @@
                 "sha256:0c5b78adfbf7762415433f5515cd5c9e762339e23369dbe8000d84a4bf4ab3af",
                 "sha256:c2de3a60e9e7d07be26b7f2b00ca0309c207e06c100f9cc2a94931fc75a478fc"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3, 3.4'",
             "version": "==0.16"
         },
         "enum-compat": {
@@ -284,6 +296,7 @@
                 "sha256:6e996bc24ebe327558f24efd106f1be5f0c033c8cbb6eed815631f73d487f1c9",
                 "sha256:efdbf9d15b18f72b7c348dd360f30e7cf3e73aa67ff832d5343eb5aa1115f250"
             ],
+            "markers": "python_version >= '3.6' and python_version < '4.0'",
             "version": "==1.3.1"
         },
         "flake8-polyfill": {
@@ -355,16 +368,18 @@
         },
         "identify": {
             "hashes": [
-                "sha256:3139bf72d81dfd785b0a464e2776bd59bdc725b4cc10e6cf46b56a0db931c82e",
-                "sha256:969d844b7a85d32a5f9ac4e163df6e846d73c87c8b75847494ee8f4bd2186421"
+                "sha256:5dd84ac64a9a115b8e0b27d1756b244b882ad264c3c423f42af8235a6e71ca12",
+                "sha256:c9504ba6a043ee2db0a9d69e43246bc138034895f6338d5aed1b41e4a73b1513"
             ],
-            "version": "==1.5.6"
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==1.5.9"
         },
         "idna": {
             "hashes": [
                 "sha256:b307872f855b18632ce0c21c5e45be78c0ea7ae4c15c828c20788b26921eb3f6",
                 "sha256:b97d804b1e9b523befed77c48dacec60e6dcb0b5391d57af6a65a312a90648c0"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.10"
         },
         "imagesize": {
@@ -372,6 +387,7 @@
                 "sha256:6965f19a6a2039c7d48bca7dba2473069ff854c36ae6f19d2cde309d998228a1",
                 "sha256:b1f6b5a4eab1f73479a50fb79fcf729514a900c341d8503d62a62dbc4127a2b1"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.2.0"
         },
         "iniconfig": {
@@ -386,6 +402,7 @@
                 "sha256:89aab215427ef59c34ad58735269eb58b1a5808103067f7bb9d5836c651b3bb0",
                 "sha256:f0a4641d3cf955324a89c04f3d94663aa4d638abe8f733ecd3582848e1c37035"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3, 3.4'",
             "version": "==2.11.2"
         },
         "markupsafe": {
@@ -424,6 +441,7 @@
                 "sha256:e249096428b3ae81b08327a63a485ad0878de3fb939049038579ac0ef61e17e7",
                 "sha256:e8313f01ba26fbbe36c7be1966a7b7424942f670f38e666995b88d012765b9be"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.1.1"
         },
         "mccabe": {
@@ -472,20 +490,22 @@
                 "sha256:4357f74f47b9c12db93624a82154e9b120fa8293699949152b22065d556079f8",
                 "sha256:998416ba6962ae7fbd6596850b80e17859a5753ba17c32284f67bfff33784181"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==20.4"
         },
         "pathspec": {
             "hashes": [
-                "sha256:7d91249d21749788d07a2d0f94147accd8f845507400749ea19c1ec9054a12b0",
-                "sha256:da45173eb3a6f2a5a487efba21f050af2b41948be6ab52b6a1e3ff22bb8b7061"
+                "sha256:86379d6b86d75816baba717e64b1a3a3469deb93bb76d613c9ce79edc5cb68fd",
+                "sha256:aa0cb481c4041bf52ffa7b0d8fa6cd3e88a2ca4879c533c9153882ee2556790d"
             ],
-            "version": "==0.8.0"
+            "version": "==0.8.1"
         },
         "pbr": {
             "hashes": [
                 "sha256:5fad80b613c402d5b7df7bd84812548b2a61e9977387a80a5fc5c396492b13c9",
                 "sha256:b236cde0ac9a6aedd5e3c34517b423cd4fd97ef723849da6b0d2231142d89c00"
             ],
+            "markers": "python_version >= '2.6'",
             "version": "==5.5.1"
         },
         "pep8-naming": {
@@ -498,10 +518,11 @@
         },
         "pipenv": {
             "hashes": [
-                "sha256:448ac3a36443db633d52a2359cac15ecbc4f429eab4ddd420697602b721d1c5a",
-                "sha256:eff0e10eadb330f612edfa5051d3d8e775e9e0e918c3c50361da703bd0daa035"
+                "sha256:d6ac39d1721517b23aca12cdb4c726dc318ec4d7bdede5c1220bbb81775005c3",
+                "sha256:dce1fb1a6941f98764c62b00010f52143aed19e2fcd8f100aff4fb3bb1bbbbe3"
             ],
-            "version": "==2020.8.13"
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==2020.11.4"
         },
         "pipenv-to-requirements": {
             "hashes": [
@@ -516,6 +537,7 @@
                 "sha256:15b2acde666561e1298d71b523007ed7364de07029219b604cf808bfa1c765b0",
                 "sha256:966c145cd83c96502c3c3868f50408687b38434af77734af1e9ca461a4081d2d"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==0.13.1"
         },
         "pre-commit": {
@@ -531,6 +553,7 @@
                 "sha256:366389d1db726cd2fcfc79732e75410e5fe4d31db13692115529d34069a043c2",
                 "sha256:9ca6883ce56b4e8da7e79ac18787889fa5206c79dcc67fb065376cd2fe03f342"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.9.0"
         },
         "pycodestyle": {
@@ -538,6 +561,7 @@
                 "sha256:2295e7b2f6b5bd100585ebcb1f616591b652db8a741695b3d8f5d28bdc934367",
                 "sha256:c58a7d2815e0e8d7972bf1803331fb0152f867bd89adf8a01dfd55085434192e"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.6.0"
         },
         "pyflakes": {
@@ -545,6 +569,7 @@
                 "sha256:0d94e0e05a19e57a99444b6ddcf9a6eb2e5c68d3ca1e98e90707af8152c90a92",
                 "sha256:35b2d75ee967ea93b55750aa9edbbf72813e06a66ba54438df2cfac9e3c27fc8"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.2.0"
         },
         "pygments": {
@@ -552,6 +577,7 @@
                 "sha256:381985fcc551eb9d37c52088a32914e00517e57f4a21609f48141ba08e193fa0",
                 "sha256:88a0bbcd659fcb9573703957c6b9cff9fab7295e6e76db54c9d00ae42df32773"
             ],
+            "markers": "python_version >= '3.5'",
             "version": "==2.7.2"
         },
         "pyparsing": {
@@ -559,6 +585,7 @@
                 "sha256:c203ec8783bf771a155b207279b9bccb8dea02d8f0c9e5f8ead507bc3246ecc1",
                 "sha256:ef9d7589ef3c200abe66653d3f1ab1033c3c419ae9b9bdb1240a85b024efc88b"
             ],
+            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.4.7"
         },
         "pytest": {
@@ -587,6 +614,8 @@
         },
         "pytest-profiling": {
             "hashes": [
+                "sha256:3b255f9db36cb2dd7536a8e7e294c612c0be7f7850a7d30754878e4315d56600",
+                "sha256:6bce4e2edc04409d2f3158c16750fab8074f62d404cc38eeb075dff7fcbb996c",
                 "sha256:93938f147662225d2b8bd5af89587b979652426a8a6ffd7e73ec4a23e24b7f29",
                 "sha256:999cc9ac94f2e528e3f5d43465da277429984a1c237ae9818f8cfd0b06acb019"
             ],
@@ -595,10 +624,10 @@
         },
         "pytz": {
             "hashes": [
-                "sha256:a494d53b6d39c3c6e44c3bec237336e14305e4f29bbf800b599253057fbb79ed",
-                "sha256:c35965d010ce31b23eeb663ed3cc8c906275d6be1a34393a1d73a41febf4a048"
+                "sha256:3e6b7dd2d1e0a59084bcee14a17af60c5c562cdc16d828e8eba2e683d3a7e268",
+                "sha256:5c55e189b682d420be27c6995ba6edce0c0a77dd67bfbe2ae6607134d5851ffd"
             ],
-            "version": "==2020.1"
+            "version": "==2020.4"
         },
         "pyyaml": {
             "hashes": [
@@ -622,26 +651,42 @@
                 "sha256:06b52815d4ad38d6524666e0d50fe9173533c9cc145a5779b89733284e6f688f",
                 "sha256:11116d424734fe356d8777f89d625f0df783251ada95d6261b4c36ad27a394bb",
                 "sha256:119e0355dbdd4cf593b17f2fc5dbd4aec2b8899d0057e4957ba92f941f704bf5",
+                "sha256:127a9e0c0d91af572fbb9e56d00a504dbd4c65e574ddda3d45b55722462210de",
                 "sha256:1ec66700a10e3c75f1f92cbde36cca0d3aaee4c73dfa26699495a3a30b09093c",
+                "sha256:227a8d2e5282c2b8346e7f68aa759e0331a0b4a890b55a5cfbb28bd0261b84c0",
+                "sha256:2564def9ce0710d510b1fc7e5178ce2d20f75571f788b5197b3c8134c366f50c",
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                 "sha256:2dc522e25e57e88b4980d2bdd334825dbf6fa55f28a922fc3bfa60cc09e5ef53",
                 "sha256:3a5f08039eee9ea195a89e180c5762bfb55258bfb9abb61a20d3abee3b37fd12",
+                "sha256:3dfca201fa6b326239e1bccb00b915e058707028809b8ecc0cf6819ad233a740",
                 "sha256:49461446b783945597c4076aea3f49aee4b4ce922bd241e4fcf62a3e7c61794c",
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                 "sha256:4b5a9bcb56cc146c3932c648603b24514447eafa6ce9295234767bf92f69b504",
+                "sha256:52e83a5f28acd621ba8e71c2b816f6541af7144b69cc5859d17da76c436a5427",
                 "sha256:625116aca6c4b57c56ea3d70369cacc4d62fead4930f8329d242e4fe7a58ce4b",
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                 "sha256:8ca9dca965bd86ea3631b975d63b0693566d3cc347e55786d5514988b6f5b84c",
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                 "sha256:a62162be05edf64f819925ea88d09d18b09bebf20971b363ce0c24e8b4aa14c0",
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                 "sha256:b88fa3b8a3469f22b4f13d045d9bd3eda797aa4e406fde0a2644bc92bbdd4bdd",
+                "sha256:b8a686a6c98872007aa41fdbb2e86dc03b287d951ff4a7f1da77fb7f14113e4d",
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                 "sha256:c13d311a4c4a8d671f5860317eb5f09591fbe8259676b86a85769423b544451e",
                 "sha256:c2c6c56ee97485a127555c9595c069201b5161de9d05495fbe2132b5ac104786",
+                "sha256:c32c91a0f1ac779cbd73e62430de3d3502bbc45ffe5bb6c376015acfa848144b",
                 "sha256:c3466a84fce42c2016113101018a9981804097bacbab029c2d5b4fcb224b89de",
+                "sha256:c454ad88e56e80e44f824ef8366bb7e4c3def12999151fd5c0ea76a18fe9aa3e",
                 "sha256:c8a2b7ccff330ae4c460aff36626f911f918555660cc28163417cb84ffb25789",
                 "sha256:cb905f3d2e290a8b8f1579d3984f2cfa7c3a29cc7cba608540ceeed18513f520",
                 "sha256:cfcf28ed4ce9ced47b9b9670a4f0d3d3c0e4d4779ad4dadb1ad468b097f808aa",
                 "sha256:dd3e6547ecf842a29cf25123fbf8d2461c53c8d37aa20d87ecee130c89b7079b",
+                "sha256:de7fd57765398d141949946c84f3590a68cf5887dac3fc52388df0639b01eda4",
                 "sha256:ea37320877d56a7f0a1e6a625d892cf963aa7f570013499f5b8d5ab8402b5625",
                 "sha256:f1fce1e4929157b2afeb4bb7069204d4370bab9f4fc03ca1fbec8bd601f8c87d",
                 "sha256:f43109822df2d3faac7aad79613f5f02e4eab0fc8ad7932d2e70e2a83bd49c26"
@@ -653,6 +698,7 @@
                 "sha256:b3559a131db72c33ee969480840fff4bb6dd111de7dd27c8ee1f820f4f00231b",
                 "sha256:fe75cc94a9443b9246fc7049224f75604b113c36acb93f87b80ed42c44cbb898"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3, 3.4'",
             "version": "==2.24.0"
         },
         "six": {
@@ -660,6 +706,7 @@
                 "sha256:30639c035cdb23534cd4aa2dd52c3bf48f06e5f4a941509c8bafd8ce11080259",
                 "sha256:8b74bedcbbbaca38ff6d7491d76f2b06b3592611af620f8426e82dddb04a5ced"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.15.0"
         },
         "snowballstemmer": {
@@ -671,10 +718,11 @@
         },
         "sphinx": {
             "hashes": [
-                "sha256:321d6d9b16fa381a5306e5a0b76cd48ffbc588e6340059a729c6fdd66087e0e8",
-                "sha256:ce6fd7ff5b215af39e2fcd44d4a321f6694b4530b6f2b2109b64d120773faea0"
+                "sha256:1c21e7c5481a31b531e6cbf59c3292852ccde175b504b00ce2ff0b8f4adc3649",
+                "sha256:3abdb2c57a65afaaa4f8573cbabd5465078eb6fd282c1e4f87f006875a7ec0c7"
             ],
-            "version": "==3.2.1"
+            "markers": "python_version >= '3.5'",
+            "version": "==3.3.0"
         },
         "sphinx-rtd-theme": {
             "hashes": [
@@ -689,6 +737,7 @@
                 "sha256:806111e5e962be97c29ec4c1e7fe277bfd19e9652fb1a4392105b43e01af885a",
                 "sha256:a072735ec80e7675e3f432fcae8610ecf509c5f1869d17e2eecff44389cdbc58"
             ],
+            "markers": "python_version >= '3.5'",
             "version": "==1.0.2"
         },
         "sphinxcontrib-devhelp": {
@@ -696,6 +745,7 @@
                 "sha256:8165223f9a335cc1af7ffe1ed31d2871f325254c0423bc0c4c7cd1c1e4734a2e",
                 "sha256:ff7f1afa7b9642e7060379360a67e9c41e8f3121f2ce9164266f61b9f4b338e4"
             ],
+            "markers": "python_version >= '3.5'",
             "version": "==1.0.2"
         },
         "sphinxcontrib-htmlhelp": {
@@ -703,6 +753,7 @@
                 "sha256:3c0bc24a2c41e340ac37c85ced6dafc879ab485c095b1d65d2461ac2f7cca86f",
                 "sha256:e8f5bb7e31b2dbb25b9cc435c8ab7a79787ebf7f906155729338f3156d93659b"
             ],
+            "markers": "python_version >= '3.5'",
             "version": "==1.0.3"
         },
         "sphinxcontrib-jsmath": {
@@ -710,6 +761,7 @@
                 "sha256:2ec2eaebfb78f3f2078e73666b1415417a116cc848b72e5172e596c871103178",
                 "sha256:a9925e4a4587247ed2191a22df5f6970656cb8ca2bd6284309578f2153e0c4b8"
             ],
+            "markers": "python_version >= '3.5'",
             "version": "==1.0.1"
         },
         "sphinxcontrib-qthelp": {
@@ -717,6 +769,7 @@
                 "sha256:4c33767ee058b70dba89a6fc5c1892c0d57a54be67ddd3e7875a18d14cba5a72",
                 "sha256:bd9fc24bcb748a8d51fd4ecaade681350aa63009a347a8c14e637895444dfab6"
             ],
+            "markers": "python_version >= '3.5'",
             "version": "==1.0.3"
         },
         "sphinxcontrib-serializinghtml": {
@@ -724,14 +777,16 @@
                 "sha256:eaa0eccc86e982a9b939b2b82d12cc5d013385ba5eadcc7e4fed23f4405f77bc",
                 "sha256:f242a81d423f59617a8e5cf16f5d4d74e28ee9a66f9e5b637a18082991db5a9a"
             ],
+            "markers": "python_version >= '3.5'",
             "version": "==1.1.4"
         },
         "toml": {
             "hashes": [
-                "sha256:926b612be1e5ce0634a2ca03470f95169cf16f939018233a670519cb4ac58b0f",
-                "sha256:bda89d5935c2eac546d648028b9901107a595863cb36bae0c73ac804a9b4ce88"
+                "sha256:806143ae5bfb6a3c6e736a764057db0e6a0e05e338b5630894a5f779cabb4f9b",
+                "sha256:b3bda1d108d5dd99f4a20d24d9c348e91c4db7ab1b749200bded2f839ccbe68f"
             ],
-            "version": "==0.10.1"
+            "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==0.10.2"
         },
         "typed-ast": {
             "hashes": [
@@ -774,7 +829,6 @@
                 "sha256:99d4073b617d30288f569d3f13d2bd7548c3a7e4c8de87db09a9d29bb3a4a60c",
                 "sha256:dafc7639cde7f1b6e1acc0f457842a83e722ccca8eef5270af2d74792619a89f"
             ],
-            "index": "pypi",
             "version": "==3.7.4.3"
         },
         "urllib3": {
@@ -782,6 +836,7 @@
                 "sha256:8d7eaa5a82a1cac232164990f04874c594c9453ec55eef02eab885aa02fc17a2",
                 "sha256:f5321fbe4bf3fefa0efd0bfe7fb14e90909eb62a48ccda331726b4319897dd5e"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3, 3.4' and python_version < '4'",
             "version": "==1.25.11"
         },
         "virtualenv": {
@@ -789,6 +844,7 @@
                 "sha256:b0011228208944ce71052987437d3843e05690b2f23d1c7da4263fde104c97a2",
                 "sha256:b8d6110f493af256a40d65e29846c69340a947669eec8ce784fcf3dd3af28380"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==20.1.0"
         },
         "virtualenv-clone": {
@@ -796,6 +852,7 @@
                 "sha256:07e74418b7cc64f4fda987bf5bc71ebd59af27a7bc9e8a8ee9fd54b1f2390a27",
                 "sha256:665e48dd54c84b98b71a657acb49104c54e7652bce9c1c4f6c6976ed4c827a29"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==0.5.4"
         }
     }

pytube/monostate.py

@@ -2,10 +2,8 @@
 from typing import Any
 from typing import Optional
 
-from typing_extensions import Protocol
 
-
-class OnProgress(Protocol):
+class OnProgress():
     def __call__(
         self, stream: Any, chunk: bytes, bytes_remaining: int
     ) -> None:
@@ -24,7 +22,7 @@ class OnProgress(Protocol):
         ...
 
 
-class OnComplete(Protocol):
+class OnComplete():
     def __call__(self, stream: Any, file_path: Optional[str]) -> None:
         """On download complete handler function.