code: def _IsMessageSetExtension(field):
      return (
          field.is_extension
          and field.containing_type.has_options
          and field.containing_type.GetOptions().message_set_wire_format
          and field.type == descriptor.FieldDescriptor.TYPE_MESSAGE
          and field.label == descriptor.FieldDescriptor.LABEL_OPTIONAL
      )
  
imports: import collections
  import warnings
  from google.protobuf import descriptor
  from google.protobuf import descriptor_database
  from google.protobuf import text_encoding
label_desc: Use image node_id 4 for calling a global function with example usage: _IsMessageSetExtension(field) and returns: unknown