How to use the recast.types.eachField function in recast

// Assume no side effects until we find out otherwise.
    var result = false;

    function check(child) {
      if (result) {
        // Do nothing.
      } else if (isArray.check(child)) {
        child.some(check);
      } else if (n.Node.check(child)) {
        assert.strictEqual(result, false);
        result = predicate(child);
      }
      return result;
    }

    types.eachField(node, function(name, child) {
      check(child);
    });

    return result;
  }