'Extends the event sequences by adding the new samples.
Args:
pianoroll_seqs: A collection of PianorollSequences to append `samples` to.
samples: A collection of binary arrays with active pitches set to 1 and
inactive pitches set to 0, which will be added to the corresponding
`pianoroll_seqs`.
Raises:
ValueError: if inputs are not of equal length.'

def extend_event_sequences(self, pianoroll_seqs, samples):

    if (len(pianoroll_seqs) != len(samples)):
        raise ValueError('`pianoroll_seqs`    and    `samples`    must    have    equal    lengths.')
    for (pianoroll_seq, sample) in zip(pianoroll_seqs, samples):
        event = tuple(np.where(sample)[0])
        pianoroll_seq.append(event)
