[Python] getElementsByClass throws ValueError: not enough values to unpack (expected 2, got 0)

I have checked out music21 getElementsByClass not showing any output for class stream.Voice but to no avail.

midi_data = converter.parse(data_fn)
# Get melody part, compress into single voice.
melody_stream = midi_data[5] # For Metheny piece, Melody is Part #5.
melody1, melody2 = melody_stream.getElementsByClass(stream.Voice)


Error:

---> 29 melody1, melody2 = melody_stream.getElementsByClass(stream.Voice)
30 for j in melody2:
31 melody1.insert(j.offset, j)

ValueError: not enough values to unpack (expected 2, got 0)


I have tried .recurse() and [stream.Voice] but to no avail.

Continue reading...