Source

File: wp-includes/class-requests.php

public static function decompress($data) {
		if (substr($data, 0, 2) !== "\x1f\x8b" && substr($data, 0, 2) !== "\x78\x9c") {
			// Not actually compressed. Probably cURL ruining this for us.
			return $data;
		}

		if (function_exists('gzdecode') && ($decoded = @gzdecode($data)) !== false) {
			return $decoded;
		}
		elseif (function_exists('gzinflate') && ($decoded = @gzinflate($data)) !== false) {
			return $decoded;
		}
		elseif (($decoded = self::compatible_gzinflate($data)) !== false) {
			return $decoded;
		}
		elseif (function_exists('gzuncompress') && ($decoded = @gzuncompress($data)) !== false) {
			return $decoded;
		}

		return $data;
	}