import math


def get_unit_normal(normal):
    """
    Calculate the unit normal of a normal.
    Eg: Unit normal of [0, 0, 4] is [0, 0, 1]
    :param normal:
    :return: List of normal vertices
    """
    squared_length = 0
    for vertex in normal:
        squared_length += vertex ** 2
    length = math.sqrt(squared_length)
    unit_normal = list(map(lambda x: x / length, normal))
    return unit_normal