Update app.py

app.py

@@ -6,7 +6,7 @@ class ValidationException(Exception):
 def string_to_int(size_str: str):
     mappings = {'M': 10**6, 'B': 10**9, 'T': 10**12}
     suffix = size_str.upper()[-1]
-    size = size_str.[:-1]
+    size = size_str[:-1]
     try:
         size = float(size)
     except ValueError: