A primer sequence can be given to the model to prepare it before the generation. This is used extensively with Magenta and is really useful if you want the model to generate something that is inspired by your primer. You can either prime the model with a hardcoded sequence or directly from a MIDI file. The priming sequence is fed to the model before the generation starts.
The string representation of the --primer_drumsflag reads as follows: you enter a list of tuples, each tuple corresponding to a step, with each tuple containing the MIDI notes being played at the same time. In this example, on the first step, both MIDI notes, 36 and 42, are played at the same time, followed by 3 steps of silence, then ...
