function _assertSingleLink(input) {
  ("production" !== process.env.NODE_ENV ? invariant(
    input.props.checkedLink == null || input.props.valueLink == null,
    'Cannot provide a checkedLink and a valueLink. If you want to use ' +
    'checkedLink, you probably don\'t want to use valueLink and vice versa.'
  ) : invariant(input.props.checkedLink == null || input.props.valueLink == null));
}
@param {ReactComponent} input Form component
@return {*} current value of the input either from value prop or link.