formFieldReferencesOtherKey = function (formField) {
      var referencedKey = _.isString(formField) ?
        formField :
        formField.key;
      if (!referencedKey) {
        return false;
      }
      return !_.include(keys, referencedKey) &&
        !_.find(keys, function (key) {
          return (referencedKey.indexOf(key + '.') === 0) ||
            (referencedKey.indexOf(key + '[]') === 0);
        });
    }
Helper function that parses the given field and returns true if
it references a key that is not in the list of keys to include.
Note the function does not parse the potential children of the field
and will thus return false even if the field actually references a key
to include indirectly.

@function
@param {Object} formField The form field to parse
@return {boolean} true when the field references one of the keys to
 include, false when not