def _occurrence_intersection(occ_P, occ_Q):
    """Computes the intersection between two occurrences.

    Parameters
    ----------
    occ_P : list of tuples
        (onset, midi) pairs representing the reference occurrence.
    occ_Q : list
        second list of (onset, midi) tuples

    Returns
    -------
    S : set
        Set of the intersection between occ_P and occ_Q.

    """
    set_P = set([tuple(onset_midi) for onset_midi in occ_P])
    set_Q = set([tuple(onset_midi) for onset_midi in occ_Q])
    return set_P & set_Q
Computes the intersection between two occurrences.

    Parameters
    ----------
    occ_P : list of tuples
        (onset, midi) pairs representing the reference occurrence.
    occ_Q : list
        second list of (onset, midi) tuples

    Returns
    -------
    S : set
        Set of the intersection between occ_P and occ_Q.