Function IsHexDigit

library/cpp/yson/writer.cpp:35–37

        }

        inline bool IsHexDigit(char c) {
            return (c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') || (c >= 'a' && c <= 'f');
        }

        inline bool IsOctDigit(char c) {
            return c >= '0' && c <= '7';