def __init__(self, name, full_name, index, number, type, cpp_type, label,
               default_value, message_type, enum_type, containing_type,
               is_extension, extension_scope, options=None,
               serialized_options=None,
               has_default_value=True, containing_oneof=None, json_name=None,
               file=None, create_key=None):  # pylint: disable=redefined-builtin
    """The arguments are as described in the description of FieldDescriptor
    attributes above.

    Note that containing_type may be None, and may be set later if necessary
    (to deal with circular references between message types, for example).
    Likewise for extension_scope.
    """
    if create_key is not _internal_create_key:
      _Deprecated('FieldDescriptor')

    super(FieldDescriptor, self).__init__(
        options, serialized_options, 'FieldOptions')
    self.name = name
    self.full_name = full_name
    self.file = file
    self._camelcase_name = None
    if json_name is None:
      self.json_name = _ToJsonName(name)
    else:
      self.json_name = json_name
    self.index = index
    self.number = number
    self.type = type
    self.cpp_type = cpp_type
    self.label = label
    self.has_default_value = has_default_value
    self.default_value = default_value
    self.containing_type = containing_type
    self.message_type = message_type
    self.enum_type = enum_type
    self.is_extension = is_extension
    self.extension_scope = extension_scope
    self.containing_oneof = containing_oneof
    if api_implementation.Type() == 'cpp':
      if is_extension:
        self._cdescriptor = _message.default_pool.FindExtensionByName(full_name)
      else:
        self._cdescriptor = _message.default_pool.FindFieldByName(full_name)
    else:
      self._cdescriptor = None
The arguments are as described in the description of FieldDescriptor
    attributes above.

    Note that containing_type may be None, and may be set later if necessary
    (to deal with circular references between message types, for example).
    Likewise for extension_scope.
    
deps/protobuf/python/google/protobuf/descriptor.py