title: What data type should Variables be when making GraphQL queries/mutations?
body: <p>How would one execute a graphQL query/mutation with variables? 
  I'm using this client: <a href="https://github.com/graphql-dotnet/graphql-client" rel="nofollow noreferrer">https://github.com/graphql-dotnet/graphql-client</a></p>
  
  <p>I'm trying to perform the following:</p>
  
  <p><a href="https://help.shopify.com/en/api/custom-storefronts/storefront-api/guides/updating-customers#creating-the-customer" rel="nofollow noreferrer">https://help.shopify.com/en/api/custom-storefronts/storefront-api/guides/updating-customers#creating-the-customer</a></p>
  
  <pre><code>mutation customerCreate($input: CustomerCreateInput!) {
        customerCreate(input: $input) {
          userErrors {
            field
            message
          }
          customer {
            id
          }
        }
      }
  </code></pre>
  
  <p>Variables:</p>
  
  <pre><code>{
    "input": {
      "email": "user@example.com",
      "password": "HiZqFuDvDdQ7"
    }
  }
  </code></pre>
  
  <p>my code:</p>
  
  <pre><code>    var request = new GraphQLRequest();
      request.Query = @"mutation customerCreate($input: CustomerCreateInput!) {
            customerCreate(input: $input) {
              userErrors {
                field
                message
              }
              customer {
                id
              }
            }
          }";
  
      request.OperationName = "customerCreate";
      request.Variables = new
      {
          email = "user@example.com",
          password = "HiZqFuDvDdQ7"
      };
  
      var client = new GraphQLClient("https://kitkatco.myshopify.com/api/graphql");
      client.DefaultRequestHeaders.Add("X-Shopify-Storefront-Access-Token", new List&lt;string&gt; { "d021132503b1357116d5f1e51abd9f39" });
      var response = await client.PostAsync(request);
  </code></pre>