src/Zend/Filter.php
public function filter($value)
    {
        $valueFiltered = $value;
        foreach ($this->_filters as $filter) {
            $valueFiltered = $filter->filter($valueFiltered);
        }
        return $valueFiltered;
    }
public function filter($value)
    {
        $valueFiltered = $value;
        foreach ($this->_filters as $filter) {
            $valueFiltered = $filter->filter($valueFiltered);
        }
        return $valueFiltered;
    }
Returns $value filtered through each filter in the chain

Filters are run in the order in which they were added to the chain (FIFO)

@param  mixed $value
@return mixed