code: function (ast) {
      assertErr(ast.kind === Kind.STRING,
        GraphQLError, 'Query error: Can only parse strings to dates but got a: ' + ast.kind, [ast])
  
      var result = new Date(ast.value)
      assertErr(!isNaN(result.getTime()),
        GraphQLError, 'Query error: Invalid date', [ast])
      assertErr(ast.value === result.toJSON(),
        GraphQLError, 'Query error: Invalid date format, only accepts: YYYY-MM-DDTHH:MM:SS.SSSZ', [ast])
  
      return result
    }
docs: Parse ast literal to date
  @param  {Object} ast graphql ast
  @return {Date} date value