code: def expect_token(lexer: Lexer, kind: TokenKind) -> Token:
      
      token = lexer.token
      if token.kind == kind:
          lexer.advance()
          return token
  
      raise GraphQLSyntaxError(
          lexer.source, token.start, f"Expected {kind.value}, found {token.kind.value}"
      )
docs: Expect the next token to be of the given kind.
  
      If the next token is of the given kind, return that token after advancing the lexer.
      Otherwise, do not change the parser state and throw an error.