refactor: replace string concatenations with f-strings

youtube/proto.py

@@ -76,7 +76,7 @@ def read_varint(data):
         except IndexError:
             if i == 0:
                 raise EOFError()
-            raise Exception('Unterminated varint starting at ' + str(data.tell() - i))
+            raise Exception(f'Unterminated varint starting at {data.tell() - i}')
         result |= (byte & 127) << 7*i
         if not byte & 128:
             break
@@ -118,7 +118,7 @@ def read_protobuf(data):
         elif wire_type == 5:
             value = data.read(4)
         else:
-            raise Exception("Unknown wire type: " + str(wire_type) + " at position " + str(data.tell()))
+            raise Exception(f"Unknown wire type: {wire_type} at position {data.tell()}")
         yield (wire_type, field_number, value)
 
 
@@ -170,8 +170,7 @@ def _make_protobuf(data):
             elif field[0] == 2:
                 result += string(field[1], _make_protobuf(field[2]))
             else:
-                raise NotImplementedError('Wire type ' + str(field[0])
-                    + ' not implemented')
+                raise NotImplementedError(f'Wire type {field[0]} not implemented')
         return result
     return data
 
@@ -218,4 +217,4 @@ def b64_to_bytes(data):
     if isinstance(data, bytes):
         data = data.decode('ascii')
     data = data.replace("%3D", "=")
-    return base64.urlsafe_b64decode(data + "="*((4 - len(data) % 4) % 4))
+    return base64.urlsafe_b64decode(f'{data}={"=" * ((4 - len(data) % 4) % 4)}')