Function get_len_of_range_longs

Return number of items in range (lo, hi, step), when arguments are * PyInt or PyLong objects. step > 0 required. Return a value < 0 if * & only if the true value is too large to fit in a signed long. * Arguments MUST return 1 with either PyInt_Check() or * PyLong_Check(). Return -1 when there is an error. */