return (ch === 0x24) || (ch === 0x5F) ||  // $ (dollar) and _ (underscore)
            (ch >= 0x41 && ch <= 0x5A) ||         // A..Z
            (ch >= 0x61 && ch <= 0x7A) ||         // a..z
            (ch === 0x5C) ||                      // \ (backslash)