Enhance type hinting in app.py for convert_local_file and convert_from_url functions

src/app.py

@@ -1,5 +1,6 @@
 import os
 from pathlib import Path
+from typing import *
 from urllib.parse import urlparse
 
 import convertapi
@@ -11,12 +12,12 @@ convertapi.api_credentials = os.getenv("CONVERTAPI_TOKEN")
 
 
 # Function to convert a local file
-def convert_local_file(local_file_path, output_format):
+def convert_local_file(local_file_path: str, output_format: str) -> str:
     """
     Convert a local document to a different format.
 
     Args:
-        local_file_path (str): The path to the input file.
+        local_file_path (str): The path to the input file provided by Gradio.
         output_format (str): The format to convert the file to.
 
     Returns:
@@ -47,7 +48,7 @@ def convert_local_file(local_file_path, output_format):
 
 
 # Function to convert a file from a URL
-def convert_from_url(document_url, output_format):
+def convert_from_url(document_url: str, output_format: str) -> str:
     """
     Convert a document from a URL to a different format.