system/HTTP/Negotiate.php
public function encoding(array $supported = []): string
	{
		array_push($supported, 'identity');

		return $this->getBestMatch($supported, $this->request->getHeaderLine('accept-encoding'));
	}
public function encoding(array $supported = []): string
	{
		array_push($supported, 'identity');

		return $this->getBestMatch($supported, $this->request->getHeaderLine('accept-encoding'));
	}
Determines the best encoding type to use based on the $supported
types the application says it supports, and the types requested
by the client.

If no match is found, the first, highest-ranking client requested
type is returned.

@param array $supported

@return string