title: How can I get all piano parts from a music21 score?
body: <p>I'm able to get all the parts in a music21.stream.Score, using</p>
  
  <pre><code>s = music21.stream.Score()
  s.getElementsByClass(music21.instrument.Instrument)
  </code></pre>
  
  <p>or </p>
  
  <pre><code>music21.instrument.partitionByInstrument(s)
  </code></pre>
  
  <p>But I cannot find a way to check whether each Part is using a Piano instrument. Is there a better way to do that?</p>