code: public function remove($name)
      {
          $name = strtolower($name);
          if (isset($this->_headers[$name])) {
              $value = $this->_headers[$name];
              unset($this->_headers[$name]);
              return $value;
          }
  
          return null;
      }
docs: Removes a header.
  @param string $name the name of the header to be removed.
  @return array the value of the removed header. Null is returned if the header does not exist.