Rotate matrix in Python

rotation.py

def swap(matrix, r1, c1, r2, c2):
    matrix[r1][c1], matrix[r2][c2] = matrix[r2][c2], matrix[r1][c1]

def transpose(matrix):
    for row in range(len(matrix)):
        for col in range(row):
            swap(matrix, row, col, col, row)

def flip_vertical(matrix):
    size = len(matrix)
    for row in range(size // 2):
        for col in range(size):
            swap(matrix, row, col, size - row - 1, col)

def rotate(matrix):
    transpose(matrix)
    flip_vertical(matrix)

A = [[1, 2, 3],
     [4, 5, 6],
     [7, 8, 9]]

rotate(A)
print(A)