object.c:530
static VALUE
sym_inspect(sym)
    VALUE sym;
{
    VALUE str;
    char *name;
    ID id = SYM2ID(sym);

    name = rb_id2name(id);
    str = rb_str_new(0, strlen(name)+1);
    RSTRING(str)->ptr[0] = ':';
    strcpy(RSTRING(str)->ptr+1, name);
    if (rb_is_junk_id(id)) {
	str = rb_str_dump(str);
	strncpy(RSTRING(str)->ptr, ":\"", 2);
    }
    return str;
}
