How to use the chempy.cpv.normalize function in chempy

def planeFromPoints(p1, p2, p3, vm1=None, vm2=None, center=True, settings={}):
    v1 = cpv.sub(p1, p2)
    v2 = cpv.sub(p3, p2)
    normal = cpv.cross_product(v1, v2)

    if 'translate' in settings:
        vtran = cpv.scale(cpv.normalize(normal), settings['translate'])
        p1_t = cpv.sub(p1, vtran)
        p2_t = cpv.sub(p2, vtran)
        p3_t = cpv.sub(p3, vtran)
        print("New coordinates are:")
        print_info("New", p1_t, p2_t, p3_t)
        print("New coordinates are for normalized plane:")
        v1_t = cpv.normalize(cpv.sub(p1_t, p2_t))
        v2_t = cpv.normalize(cpv.sub(p3_t, p2_t))
        normal_t = cpv.normalize(cpv.cross_product(v1_t, v2_t))
        v2_t = cpv.normalize(cpv.cross_product(normal_t, v1_t))
        p1_t2 = cpv.add(v1_t, p2_t)
        p3_t2 = cpv.add(v2_t, p2_t)
        print_info("Newnormal", p1_t2, p2_t, p3_t2)

    if vm1!=None:
        v1 = cpv.scale(cpv.normalize(v1), vm1)
    if vm2!=None:
        v2 = cpv.scale(cpv.normalize(v2), vm2)

    centrum = p2
    if center:
        corner1 = cpv.add(cpv.add(centrum, v1), v2)
        corner2 = cpv.sub(cpv.add(centrum, v1), v2)
        corner3 = cpv.sub(cpv.sub(centrum, v1), v2)

def planeFromPoints(p1, p2, p3, vm1=None, vm2=None, center=True, settings={}):
    v1 = cpv.sub(p1, p2)
    v2 = cpv.sub(p3, p2)
    normal = cpv.cross_product(v1, v2)

    if 'translate' in settings:
        vtran = cpv.scale(cpv.normalize(normal), settings['translate'])
        p1_t = cpv.sub(p1, vtran)
        p2_t = cpv.sub(p2, vtran)
        p3_t = cpv.sub(p3, vtran)
        print("New coordinates are:")
        print_info("New", p1_t, p2_t, p3_t)
        print("New coordinates are for normalized plane:")
        v1_t = cpv.normalize(cpv.sub(p1_t, p2_t))
        v2_t = cpv.normalize(cpv.sub(p3_t, p2_t))
        normal_t = cpv.normalize(cpv.cross_product(v1_t, v2_t))
        v2_t = cpv.normalize(cpv.cross_product(normal_t, v1_t))
        p1_t2 = cpv.add(v1_t, p2_t)
        p3_t2 = cpv.add(v2_t, p2_t)
        print_info("Newnormal", p1_t2, p2_t, p3_t2)

    if vm1!=None:
        v1 = cpv.scale(cpv.normalize(v1), vm1)
    if vm2!=None:
        v2 = cpv.scale(cpv.normalize(v2), vm2)

    centrum = p2
    if center:
        corner1 = cpv.add(cpv.add(centrum, v1), v2)
        corner2 = cpv.sub(cpv.add(centrum, v1), v2)
        corner3 = cpv.sub(cpv.sub(centrum, v1), v2)

def planeFromPoints(point1, point2, point3, facetSize):
    v1 = cpv.normalize(cpv.sub(point2, point1))
    v2 = cpv.normalize(cpv.sub(point3, point1))
    normal = cpv.cross_product(v1, v2)
    v2 = cpv.cross_product(normal, v1)
    x = cpv.scale(v1, facetSize)
    y = cpv.scale(v2, facetSize)
    center = point2
    corner1 = cpv.add(cpv.add(center, x), y)
    corner2 = cpv.sub(cpv.add(center, x), y)
    corner3 = cpv.sub(cpv.sub(center, x), y)
    corner4 = cpv.add(cpv.sub(center, x), y)
    return plane(corner1, corner2, corner3, corner4, normal)

helix_orientation
    '''
    visualize, quiet = int(visualize), int(quiet)
    stored.x = dict()
    cmd.iterate_state(STATE, '(%s) and name N+C' % (selection),
                      'stored.x.setdefault(chain + resi, dict())[name] = x,y,z')
    vec = cpv.get_null()
    count = 0
    for x in stored.x.values():
        if 'C' in x and 'N' in x:
            vec = cpv.add(vec, cpv.sub(x['C'], x['N']))
            count += 1
    if count == 0:
        print('warning: count == 0')
        raise CmdException
    vec = cpv.normalize(vec)
    return _common_orientation(selection, vec, visualize, quiet)

p3_t = cpv.sub(p3, vtran)
        print("New coordinates are:")
        print_info("New", p1_t, p2_t, p3_t)
        print("New coordinates are for normalized plane:")
        v1_t = cpv.normalize(cpv.sub(p1_t, p2_t))
        v2_t = cpv.normalize(cpv.sub(p3_t, p2_t))
        normal_t = cpv.normalize(cpv.cross_product(v1_t, v2_t))
        v2_t = cpv.normalize(cpv.cross_product(normal_t, v1_t))
        p1_t2 = cpv.add(v1_t, p2_t)
        p3_t2 = cpv.add(v2_t, p2_t)
        print_info("Newnormal", p1_t2, p2_t, p3_t2)

    if vm1!=None:
        v1 = cpv.scale(cpv.normalize(v1), vm1)
    if vm2!=None:
        v2 = cpv.scale(cpv.normalize(v2), vm2)

    centrum = p2
    if center:
        corner1 = cpv.add(cpv.add(centrum, v1), v2)
        corner2 = cpv.sub(cpv.add(centrum, v1), v2)
        corner3 = cpv.sub(cpv.sub(centrum, v1), v2)
        corner4 = cpv.add(cpv.sub(centrum, v1), v2)
    else:
        corner1 = cpv.add(cpv.add(centrum, v1), v2)
        corner2 = cpv.add(centrum, v1)
        corner3 = centrum
        corner4 = cpv.add(centrum, v2)

    return plane(corner1, corner2, corner3, corner4, normal, settings)

stored.x = dict()
    cmd.iterate_state(-1, '(%s) and name N+O' % (selection),
            'stored.x.setdefault(resv, dict())[name] = x,y,z')
    vec_list = []
    for resi in stored.x:
        resi_other = resi + 4
        if 'O' in stored.x[resi] and resi_other in stored.x:
            if 'N' in stored.x[resi_other]:
                vec = cpv.sub(stored.x[resi_other]['N'], stored.x[resi]['O'])
                if cpv.length(vec) < cutoff:
                    vec_list.append(vec)
    if len(vec_list) == 0:
        print 'warning: count == 0'
        raise CmdException
    vec = _vec_sum(vec_list)
    vec = cpv.normalize(vec)
    return _common_orientation(selection, vec, visualize, quiet)