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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 determine_lengths(dtrajs):
 r""" Determines the lengths of all trajectories Parameters dtrajs : list of int-arrays discrete trajectories """

    if (isinstance(dtrajs[0], (int))):
        return len(dtrajs) * np.ones((1))
    lengths = np.zeros((len(dtrajs)))
    for i in range(len(dtrajs)):
        lengths[i] = len(dtrajs[i])
    return lengths