class_docstr: Common class for descriptors that can be nested.
class_docstr_tok: ["Common","class","for","descriptors","that","can","be","nested","."]
docstr: Copies this to the matching proto in descriptor_pb2.
  
  Args:
    proto: An empty proto instance from descriptor_pb2.
  
  Raises:
    Error: If self couldn't be serialized, due to to few constructor
      arguments.
code: def CopyToProto(self, proto):
      """Copies this to the matching proto in descriptor_pb2.
  
      Args:
        proto: An empty proto instance from descriptor_pb2.
  
      Raises:
        Error: If self couldn't be serialized, due to to few constructor
          arguments.
      """
      if (
          self.file is not None
          and self._serialized_start is not None
          and self._serialized_end is not None
      ):
          proto.ParseFromString(
              self.file.serialized_pb[
                  self._serialized_start : self._serialized_end
              ]
          )
      else:
          raise Error("Descriptor does not contain serialization.")
  
imports: import threading
  import warnings
  import six
  from google.protobuf.internal import api_implementation
label_desc: Use image node_id 2 for calling the _NestedDescriptorBase obj's underlying member method code with example usage: obj.CopyToProto(proto) without return types