fileseq.go
func toRange(start, end, step int) []int {
	nums := []int{}
	if step < 1 {
		step = 1
	}
	if start <= end {
		for i := start; i <= end; {
			nums = append(nums, i)
			i += step
		}
	} else {
		for i := start; i >= end; {
			nums = append(nums, i)
			i -= step
		}
	}
	return nums
}
func toRange(start, end, step int) []int {
	nums := []int{}
	if step < 1 {
		step = 1
	}
	if start <= end {
		for i := start; i <= end; {
			nums = append(nums, i)
			i += step
		}
	} else {
		for i := start; i >= end; {
			nums = append(nums, i)
			i -= step
		}
	}
	return nums
}
// Expands a start, end, and stepping value
// into the full range of int values.