function _shouldTrigger (keydownThis, keydownNext) {
      if (!(keydownNext && keydownNext.event && !keydownThis.event)) return false;

      return ( keySets.some( keySet => matchKeys( { keySet, event: keydownNext.event } ) ) )
    }
_shouldTrigger

@access private
@param {object} thisProps Exsting props from the wrapped component
@param {object} thisProps.keydown The namespaced state from the higher-order
component (class_decorator)
@param {object} nextProps The incoming props from the wrapped component
@param {object} nextProps.keydown The namescaped state from the higher-order
component (class_decorator)
@param {array} keys The keys bound to the decorated method
@return {boolean} Whether all tests have passed