code: def unexpected(parser, at_token=None):
      """Helper function for creating an error when an unexpected lexed token
      is encountered."""
      token = at_token or parser.token
      return GraphQLSyntaxError(
          parser.source,
          token.start,
          "Unexpected {}".format(get_token_desc(token)),
      )
  
imports: from .None import ast
  from ..error import GraphQLSyntaxError
  from .lexer import Lexer, TokenKind, get_token_desc, get_token_kind_desc
  from .source import Source
label_desc: Use image node_id 9 for calling a global function with example usage: unexpected(parser, at_token) and returns: GraphQLSyntaxError