title: How do I specify a graphql type that takes multiple types?
body: <p>I want to create a graphql type that can return either an <code>Array of Integers</code> or <code>String</code>.</p>
  
  <p>I've already tried using union in the form
  <code>union CustomVal = [Int] | String</code>, but this returns an error.</p>
  
  <p>The schema declaration is:</p>
  
  <pre><code>union CustomValues = [Int] | String
  
  type Data {
      name: String
      slug: String
      selected: Boolean
      values: CustomValues
  }
  </code></pre>
  
  <p>The error is:</p>
  
  <pre><code>node_modules/graphql/error/syntaxError.js:24
  return new _GraphQLError.GraphQLError('Syntax Error: ' + description, undefined, source, [position]);
  Syntax Error: Expected Name, found [
  GraphQL request (81:23)
  80: 
  81:     union CustomValues = [Int] | String
  </code></pre>
  
  <p>Is this possible to do in graphql? If not, can you please suggest an alternative to do this.</p>
  
  <p>I ask this as the union documentation says that <code>Note that members of a union type need to be concrete object types; you can't create a union type out of interfaces or other unions.</code></p>
  
  <p>Any solutions would be highly helpful.</p>