Avoid to define helper method on top-level context
Avoid to define helper method on top-level context

refs: https://github.com/fastladder/fastladder/pull/48#discussion_r3403790

ykzts/fastladder,onk/fastladder,fastladder/fastladder,toshimaru/fastladder,id774/fastladder,onk/fastladder,toshimaru/fastladder,id774/fastladder,onk/fastladder,id774/fastladder,fastladder/fastladder,toshimaru/fastladder,ykzts/fastladder,fastladder/fastladder,ykzts/fastladder