function each (callable $fn)
  {
    foreach ($this->getIterator () as $k => $v)
      if ($fn ($v, $k) === false) break;
    return $this;
  }
function each (callable $fn)
  {
    foreach ($this->getIterator () as $k => $v)
      if ($fn ($v, $k) === false) break;
    return $this;
  }
function each ( callable $ fn ) { foreach ( $ this -> getIterator ( ) as $ k => $ v ) if ( $ fn ( $ v , $ k ) === false ) break ; return $ this ; }
Calls a function for every element in the iterator.

@param callable $fn A callback that receives the current value and key; it can, optionally, return `false` to break
the loop.
@return $this
Calls a function for every element in the iterator .