Flip a numeric matrix with Python 3.

flip_matrix.py

def _flip_matrix(matrix, n_90_degrees_flips):
    '''
    Let's say that we have the following matrix:
    1 , 2 , 3 , 4
    5 , 6 , 7 , 8  => [[1 , 2 , 3 , 4], [5 , 6 , 7 , 8], [9 , 10, 11, 12], [13, 14, 15, 16]]
    9 , 10, 11, 12
    13, 14, 15, 16
    And we want to flip it 1x in a way that it looks like the following
    13, 9 , 5, 1
    14, 10, 6, 2
    15, 11, 7, 3
    16, 12, 8, 4
    This function takes the square matrix and the number of flips it must perform
    as parameters and returns a new matrix
    '''
    for i in (range(n_90_degrees_flips)):
        matrix = swap_lines(transpose(matrix))
    return matrix

def transpose(matrix):
    # Creating the matrix to receive the transposition
    number_of_lines = len(matrix[0])
    number_of_columns = len(matrix)
    transpose = [[0 for i in range(number_of_columns)] for i in range(number_of_lines)]
    for i in range(number_of_lines):
        for j in range(number_of_columns):
            # Each item in the original array is being placed in the transpose
            # in the correct position
            transpose[i][j] = matrix[j][i]
    return transpose


def swap_lines(matrix):
    matrix_len = len(matrix)
    for i in range(matrix_len):
        line_len = len(matrix[i])
        first_index = 0
        last_index = line_len - 1
        while last_index > first_index:
            # swaping the numbers between first_index and last_index without aux
            matrix[i][first_index] += matrix[i][last_index]
            matrix[i][last_index] = matrix[i][first_index] - matrix[i][last_index]
            matrix[i][first_index] = matrix[i][first_index] - matrix[i][last_index]
            #first_index is incremented by one each roung
            first_index += 1
            # last_index is decremented by one each round
            last_index -= 1
    return matrix

def print_matrix(m):
    for i in range(len(m)):
        print(m[i])

# original = [[1 , 2 , 3 , 4], [5 , 6 , 7 , 8], [9 , 10, 11, 12], [13, 14, 15, 16]]
original = [[1,2 ,3], [4,5,6],[7,8,9],[10,11,12]]
print_matrix(original)
print("-------")
print_matrix(_flip_matrix(original, 1))