Adds a FileDescriptor to the pool, non-recursively.

    If the FileDescriptor contains messages or enums, the caller must explicitly
    register them.

    Args:
      file_desc: A FileDescriptor.

def AddFileDescriptor(self, file_desc):
    """Adds a FileDescriptor to the pool, non-recursively.

    If the FileDescriptor contains messages or enums, the caller must explicitly
    register them.

    Args:
      file_desc: A FileDescriptor.
    """

    self._AddFileDescriptor(file_desc)
    # TODO(jieluo): This is a temporary solution for FieldDescriptor.file.
    # Remove it when FieldDescriptor.file is added in code gen.
    for extension in file_desc.extensions_by_name.values():
      self._file_desc_by_toplevel_extension[
          extension.full_name] = file_desc