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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 get_not_unique_values(array):
    '''Returns the values that appear at least twice in array.

    Parameters
    ----------
    array : array like

    Returns
    -------
    numpy.array
    '''
    s = np.sort(array, axis=None)
    s = s[s[1:] == s[:-1]]
    return np.unique(s)