spiral order matrix

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1m = [[1,2,3],
2   [4,5,6],
3   [7,8,9]]
4
5def spiralOrder(m):
6    return m and [*m.pop(0)] + spiralOrder([*zip(*m)][::-1])
7  
8spiralOrder(m)

See also:

matrix transpose

matrix anticlockwise rotation