function passChildren() {
  return this.props.children ? React.Children.only(this.props.children) : null
}
@fileoverview Presenter is a specialized React component that
creates a boundary between "smart" and "dumb" components. This
improves testing and keeps business logic in a consistent place
(instead of spread across bunches of components).

Use Presenters to track changes to a Microcosm, push actions, and
manage application flow.
@flow