pred

VALUE
rb_int_pred(VALUE num)
{
 if (FIXNUM_P(num)) {
 long i = FIX2LONG(num) - 1;
 return LONG2NUM(i);
 }
 if (RB_TYPE_P(num, T_BIGNUM)) {
 return rb_big_minus(num, INT2FIX(1));
 }
 return num_funcall1(num, '-', INT2FIX(1));
}