I have a Bignum object and I tried calling StringValueCStr() to get it
in string form.  This raises:

(eval): cannot convert Bignum into String (TypeError)

I believe this is ultimately because this routine in string.c is being
called:

VALUE
rb_str_to_str(str)
    VALUE str;
{
    return rb_convert_type(str, T_STRING, "String", "to_str");
}

Why is to_str used here?  Should it be to_s, since only a few classes
seem to have to_str?

-- Timothy