def METHOD_NAME(p1, p2, p3):
    """
    http://stackoverflow.com/a/8135330/1243487
    finds the normal of a triangle defined by passing 3 vectors
    input: three 3-element-iterables (tuples or lists)
    output: one 3-element tuple representing the direction of the face (not normalized)
    """
    return [
        ((p2[1]-p1[1])*(p3[2]-p1[2]))-((p2[2]-p1[2])*(p3[1]-p1[1])),
        ((p2[2]-p1[2])*(p3[0]-p1[0]))-((p2[0]-p1[0])*(p3[2]-p1[2])),
        ((p2[0]-p1[0])*(p3[1]-p1[1]))-((p2[1]-p1[1])*(p3[0]-p1[0]))
    ]