title: How to generate complete AST from GraphQL input object
body: <p>I'm playing around with the <a href="https://graphql.org/graphql-js/language/#visit" rel="nofollow noreferrer">visit</a> and <a href="https://graphql.org/graphql-js/utilities/#typeinfo" rel="nofollow noreferrer">TypeInfo</a> utilities to analyse some graphql queries. I want to analyse and, eventually, modify a filter specified as a <a href="https://www.graph.cool/docs/reference/graphql-api/query-api-nia9nushae#filtering-by-field" rel="nofollow noreferrer">graphcool style input filter</a></p>
  
  <p>However, I'm not able to retrieve the information I'd expect. Given this query:</p>
  
  <pre><code>{
      Systems (filter: { code_in: ["lemon"] }) {
          code
      }
  }
  </code></pre>
  
  <p>with this code:</p>
  
  <pre class="lang-js prettyprint-override"><code>    visit(parse(systemFilter), {
          enter: node =&gt; {
              typeInfo.enter(node);
              console.log(JSON.stringify( typeInfo.getFieldDef(), null, 2))
              console.log(JSON.stringify( typeInfo.getArgument(), null, 2))
          },
          leave: node =&gt; {
              typeInfo.leave(node);
          },
      });
  
  </code></pre>
  
  <p>I don't find any references to <code>code_in</code> or <code>lemon</code> in the logs.</p>
  
  <p>Are properties of input objects less available to graphql AST tooling, or am I doing something wrong?</p>