src/ArrayIntersections.php
protected function isNoResultMask($mask) {
    foreach ($this->noResultMasks as $noresultMask) {
      if ($mask === $noresultMask) {
        return TRUE; // @codeCoverageIgnore
      }
      if (($mask & $noresultMask) === $noresultMask) {
        $this->noResultMasks[] = $mask;
        return TRUE;
      }
    }
    return FALSE;
  }
protected function isNoResultMask($mask) {
    foreach ($this->noResultMasks as $noresultMask) {
      if ($mask === $noresultMask) {
        return TRUE; // @codeCoverageIgnore
      }
      if (($mask & $noresultMask) === $noresultMask) {
        $this->noResultMasks[] = $mask;
        return TRUE;
      }
    }
    return FALSE;
  }
Try to determine if this mask will result in no intersections based on
previously generated masks.

@param string $mask
The mask to check.

@return boolean
TRUE if this mask would result in an empty intersection, FALSE if not or
if not known.