# Returns `self` to its int value
	#
	# REQUIRE: `is_hexdigit`
	fun from_hex: Int do
		if self >= '0' and self <= '9' then return code_point - 0x30
		if self >= 'A' and self <= 'F' then return code_point - 0x37
		if self >= 'a' and self <= 'f' then return code_point - 0x57
		# Happens if self is not a hexdigit
		assert self.is_hexdigit
		# To make flow analysis happy
		abort
	end