code: function introspect (text) {
    return new Promise(function (resolve, reject) {
      try {
        var astDocument = parse(text)
        var schema = buildASTSchema(astDocument)
        graphql(schema, graphqlviz.query)
          .then(function (data) {
            resolve(data)
          })
          .catch(function (e) {
            reject('Fatal error, exiting.')
            fatal(e, text)
          })
      } catch (e) {
        reject('Fatal error, exiting.')
        fatal(e, text)
      }
    })
  }
docs: given a "GraphQL schema language" text file, converts into introspection JSON