# Decode `self` from percent (or URL) encoding to a clear string
	#
	# Invalid '%' are not decoded.
	#
	#     assert "aBc09-._~".to_bytes.from_percent_encoding == "aBc09-._~".to_bytes
	#     assert "%25%28%29%3c%20%3e".to_bytes.from_percent_encoding == "%()< >".to_bytes
	#     assert ".com%2fpost%3fe%3dasdf%26f%3d123".to_bytes.from_percent_encoding == ".com/post?e=asdf&f=123".to_bytes
	#     assert "%25%28%29%3C%20%3E".to_bytes.from_percent_encoding == "%()< >".to_bytes
	#     assert "incomplete %".to_bytes.from_percent_encoding == "incomplete %".to_bytes
	#     assert "invalid % usage".to_bytes.from_percent_encoding == "invalid % usage".to_bytes
	#     assert "%c3%a9%e3%81%82%e3%81%84%e3%81%86".to_bytes.from_percent_encoding == "éあいう".to_bytes
	#     assert "%1 %A %C3%A9A9".to_bytes.from_percent_encoding == "%1 %A éA9".to_bytes
	fun from_percent_encoding: Bytes do
		var tmp = new Bytes.with_capacity(length)
		var pos = 0
		while pos < length do
			var b = self[pos]
			if b != u'%' then
				tmp.add b
				pos += 1
				continue
			end
			if length - pos < 2 then
				tmp.add u'%'
				pos += 1
				continue
			end
			var bn = self[pos + 1]
			var bnn = self[pos + 2]
			if not bn.is_valid_hexdigit or not bnn.is_valid_hexdigit then
				tmp.add u'%'
				pos += 1
				continue
			end
			tmp.add((bn.hexdigit_to_byteval << 4) + bnn.hexdigit_to_byteval)
			pos += 3
		end
		return tmp
	end