func MapIntInt64Err(f func(int) (int64, error), list []int) ([]int64, error) {
	if f == nil {
		return []int64{}, nil
	}
	newList := make([]int64, len(list))
	for i, v := range list {
		r, err := f(v)
		if err != nil {
			return nil, err
		}
		newList[i] = r
	}
	return newList, nil
}
MapIntInt64Err takes two inputs -
1. Function 2. List. Then It returns a new list after applying the function on each item of the list and error
package fp