Function most_common_measure_rhythms 

pub fn most_common_measure_rhythms(stream: &Stream) -> Vec<MeasureRhythm<'_>>

The rhythms of a stream’s measures, nested ones included, most common first, those as common in the order first met: music21’s mostCommonMeasureRhythms, without the copy of each first measure transposed to start on C5 that music21 keeps beside it.