title: How can I execute mutation in GraphQL playground?
body: <p><em>My Goal</em>: I want to execute a mutation in GraphQL Playground.</p>
  
  <p>My schema looks the following:</p>
  
  <pre><code>type Mutation {
      # Add a new comment
      addComment(comment: InputComment!): Comment
  }
  
  # Input type for a new Comment
  input InputComment {
      # The comment text
      comment: String!
      # The id of the author
      author: String!
      # The id of the talk
      talkId: Long!
  }
  </code></pre>
  
  <p>I found a lot of examples that will work if I have:</p>
  
  <pre><code>type Mutation {
      # Add a new comment
      addComment(comment: String!, author: String!, talkId: Long!): Comment
  }
  </code></pre>
  
  <p>But I can't understand how I can create an object of type <code>InputComment</code> on the fly in GraphQL Playground.</p>
  
  <p>E.g., for the last scenario I could just run:</p>
  
  <pre><code>mutation {
    addComment(
      comment: "My great comment"
      author: "The great author"
      talkId: 123
    ) {
      id
    }
  }
  </code></pre>