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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def quads_to_tris(quads):
    '''
    Convert quad faces to triangular faces.

    quads: An nx4 array.

    Return a 2nx3 array.

    '''
    import numpy as np
    tris = np.empty((2 * len(quads), 3))
    tris[0::2, :] = quads[:, [0, 1, 2]]
    tris[1::2, :] = quads[:, [0, 2, 3]]
    return tris