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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 stack_lines(indices):
 """ Stack a list of values that represent a polyline into individual line segments with duplicated consecutive values. Parameters indices: sequence of items Returns --------- stacked: (n,2) set of items In [1]: trimesh.util.stack_lines([0,1,2]) Out[1]: array([[0, 1], [1, 2]]) In [2]: trimesh.util.stack_lines([0,1,2,4,5]) Out[2]: array([[0, 1], [1, 2], [2, 4], [4, 5]]) In [3]: trimesh.util.stack_lines([[0,0],[1,1],[2,2], [3,3]]) Out[3]: array([[0, 0], [1, 1], [1, 1], [2, 2], [2, 2], [3, 3]]) """

    indices = np.asanyarray(indices)
    if is_sequence(indices[0]):
        shape = (-1, len(indices[0]))
    else:
        shape = (-1, 2)
    return np.column_stack((indices[:-1],
                            indices[1:])).reshape(shape)