Function keep_heaviest_slices 

pub fn keep_heaviest_slices(
    slices: &[MeasureSlice],
    weights: &[(Vec<u8>, FloatType)],
    maximum: usize,
    trim_below: FloatType,
) -> Vec<MeasureSlice>

The slices to keep of a measure’s, lengthened: music21’s keepHeaviestSlices.

The maximum heaviest sets of classes in weights are kept that weigh at least trim_below times the heaviest. A kept slice lasts until the next kept slice of other classes, the first starting the measure and the last lasting to its end; one starting a sixteenth, thirty-second, sixty-fourth or triplet eighth past a beat is moved onto the beat.