Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
Example 1:

Input:
[
 [ 1, 2, 3 ],
 [ 4, 5, 6 ],
 [ 7, 8, 9 ]
]
Output: [1,2,3,6,9,8,7,4,5]

Solution 1:

def spiralOrder(self, matrix):
    return matrix and [*matrix.pop(0)] + self.spiralOrder([*zip(*matrix)][::-1])