code: def create_udf_node(name, fields):
      
      definition = next(_udf_name_cache[name])
      external_name = '{}_{:d}'.format(name, definition)
      return type(external_name, (BigQueryUDFNode,), fields)
docs: Create a new UDF node type.
  
      Parameters
      ----------
      name : str
          Then name of the UDF node
      fields : OrderedDict
          Mapping of class member name to definition
  
      Returns
      -------
      result : type
          A new BigQueryUDFNode subclass