code: function validateData(data, schema, fn) {
          debug('Schema:', schema);
          debug('Data:', data);
  
          if (!tv4.validate(data, schema)) {
              return fn(tv4.error);
          }
  
          return fn(null, true);
      }
docs: Verifies that the data conforms to the schema.
  
  @arg {} data - The data to validate.
  @arg {object} schema - Valid JSON schema.
  @arg {function} fn - Node-style callback that will be passed an error
  as the first argument if the packet is invalid.