code: def parse_variable_definition(parser):
      start = parser.token.start
  
      return ast.VariableDefinition(
          variable=parse_variable(parser),
          type=expect(parser, TokenKind.COLON) and parse_type(parser),
          default_value=parse_value_literal(parser, True)
          if skip(parser, TokenKind.EQUALS)
          else None,
          loc=loc(parser, start),
      )
  
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 18 for calling a global function with example usage: parse_variable_definition(parser) and returns: ast