function parseUnionTypeDefinition()
{
$start = $this->lexer->token;
$this->expectKeyword('union');
$name = $this->parseName();
$directives = $this->parseDirectives();
$this->expect(Token::EQUALS);
$types = $this->parseUnionMembers();
return new UnionTypeDefinitionNode(['name' => $name, 'directives' => $directives, 'types' => $types, 'loc' => $this->loc($start)]);
}