Added more explcit typing to from_unicode and changed to have one return

src/icalendar/parser_tools.py

@@ -1,19 +1,21 @@
+from typing import Any
+
 SEQUENCE_TYPES = (list, tuple)
 DEFAULT_ENCODING = 'utf-8'
 
 
-def from_unicode(value, encoding='utf-8') -> bytes:
+def from_unicode(value: Any, encoding='utf-8') -> bytes:
     """
     Converts a value to bytes, even if it already is bytes
     :param value: The value to convert
     :param encoding: The encoding to use in the conversion
     :return: The bytes representation of the value
     """
     if isinstance(value, bytes):
-        return value
+        value = value
     elif isinstance(value, str):
         try:
-            return value.encode(encoding)
+            value = value.encode(encoding)
         except UnicodeEncodeError:
             value = value.encode('utf-8', 'replace')
     return value