- doc: /* Return the first character in STRING.
-A multibyte character is handled correctly.
-The value returned is a Unicode codepoint if it is below #x110000 (in
-hex). Codepoints beyond that are Emacs extensions of Unicode. In
-particular, eight-bit characters are returned as codepoints in the
-range #x3FFF80 through #x3FFFFF, inclusive. */)