public function format()
{
$headers = '';
if ($this->path) {
$headers .= $this->createHeader('PATH', $this->path);
}
if ($this->mailTo) {
$headers .= $this->createHeader('MAILTO', $this->mailTo);
}
if ($this->home) {
$headers .= $this->createHeader('HOME', $this->home);
}
if ($this->shell) {
$headers .= $this->createHeader('SHELL', $this->shell);
}
if ($this->contentType) {
$headers .= $this->createHeader('CONTENT_TYPE', $this->contentType);
}
if ($this->encoding) {
$headers .= $this->createHeader('CONTENT_TRANSFER_ENCODING', $this->encoding);
}
return $headers;
}