Restrict midi2ly to one voice

[Stephan Schöll]

Hi

I have a self-recorded/-created midi file which I have quantized and
simplified to death (lengths and durations to 1/16, no overlaps). Let's
assume it's the the left hand part of a piano score. Now I want to
convert it to a lilypond file using

midi2ly.py -d 16 -s 16 -o "<path to file>\MITM_Piano_LH.ly" "<path to
file>\MITM_Piano_LH.mid"

This works without errors on the command line. But lilypond generates 4
voices and distributes the notes all over these voices which is a mess.
I optimized the midi file in a way that midi2ly might simply produce one
voice.

How can I tell midi2ly to create only one voice? I couldn't find any
helping hint in the documentation
https://lilypond.org/doc/v2.18/Documentation/usage/invoking-midi2ly.en.html.

Best Regards
Stephan