public function headers($key = null, $value = null) {
		if (is_string($key) && strpos($key, ':') === false) {
			if ($value === null) {
				return isset($this->headers[$key]) ? $this->headers[$key] : null;
			}
			if ($value === false) {
				unset($this->headers[$key]);
				return $this->headers;
			}
		}

		if ($value) {
			$this->headers = array_merge($this->headers, array($key => $value));
		} else {
			foreach ((array) $key as $header => $value) {
				if (!is_string($header)) {
					if (preg_match('/(.*?):(.+)/i', $value, $match)) {
						$this->headers[$match[1]] = trim($match[2]);
					}
				} else {
					$this->headers[$header] = $value;
				}
			}
		}
		$headers = array();

		foreach ($this->headers as $key => $value) {
			if (is_array($value)) {
				foreach ($value as $val) {
					$headers[] = "{$key}: {$val}";
				}
				continue;
			}
			$headers[] = "{$key}: {$value}";
		}
		return $headers;
	}