แก้ไขฟังก์ชันที่ "ไม่บริสุทธิ์"

# Pass in all needed variables as parameters
def scale_list(input_list):
    new_list = []
    for item in input_list:
        # Don't rely on variables that aren't passed in as parameters
        new_item = (item - mean_shift) / scaling_value
        new_list.append(new_item)
    return new_list