merges one or more source tracks to a single destination track
of a MIDI song.
The first option is a list that designates output track.
The first element of that list is the MIDI song descriptor
for the track, and the second argument of the list is the
track in that MIDI song.
The second, and optional remaining arguments, are lists specifying
the source tracks.
The form of the source lists is the same as that for the destination
The times of events in a source track are adjusted as necessary to convert
from the division of the source track to the division of the
for a description of the division song configuration option.
All MIDI song descriptors should be values returned from a