public function filter($callback)
    {
        $this->assertMutable('Attempting to filter immutable array');
        $this->filters[] = $callback;
        $this->applyFilters();
        return $this;
    }
public function filter($callback)
    {
        $this->assertMutable('Attempting to filter immutable array');
        $this->filters[] = $callback;
        $this->applyFilters();
        return $this;
    }
public function filter ( $ callback ) { $ this -> assertMutable ( 'Attempting to filter immutable array' ) ; $ this -> filters [ ] = $ callback ; $ this -> applyFilters ( ) ; return $ this ; }
Filters Items using callback.

@param callable $callback
@return MultiValue
Filters Items using callback .