public function equals(Collection $that) : bool {
        return
            get_class($this) == get_class($that) &&
            $this->items === $that->items;
    }
public function equals(Collection $that) : bool {
        return
            get_class($this) == get_class($that) &&
            $this->items === $that->items;
    }
public function equals ( Collection $ that ) : bool { return get_class ( $ this ) == get_class ( $ that ) && $ this -> items === $ that -> items ; }
compare one collection against another. collections are
considered equal if both collection classes are of the same
type and both item arrays are considered equal with strict
comparison.

@param Collection $that
@return bool
compare one collection against another . collections are considered equal if both collection classes are of the same type and both item arrays are considered equal with strict comparison .