public function has($key)
    {
        return (isset($this->headers[$this->normalizeKey($key)])) ? true : false;
    }
public function has($key)
    {
        return (isset($this->headers[$this->normalizeKey($key)])) ? true : false;
    }
public function has ( $ key ) { return ( isset ( $ this -> headers [ $ this -> normalizeKey ( $ key ) ] ) ) ? true : false ; }
Get the header by key.

@param (string) $key The header key

@since 3.0.0

@return bool
Get the header by key .