class_docstr: Stores a polyphonic sequence as a stream of single-note events.
  
  Events are PolyphonicEvent tuples that encode event type and pitch.
class_docstr_tok: ["Stores","a","polyphonic","sequence","as","a","stream","of","single-note","events",".","Events","are","PolyphonicEvent","tuples","that","encode","event","type","and","pitch","."]
docstr: Appends the event to the end of the sequence.
  
  Args:
    event: The polyphonic event to append to the end.
  Raises:
    ValueError: If `event` is not a valid polyphonic event.
docstr_tok: ["Appends","the","event","to","the","end","of","the","sequence",".","Args",":","event",":","The","polyphonic","event","to","append","to","the","end",".","Raises",":","ValueError",":","If","`","event","`","is","not","a","valid","polyphonic","event","."]
code: def append(self, event):
      """Appends the event to the end of the sequence.
  
      Args:
        event: The polyphonic event to append to the end.
      Raises:
        ValueError: If `event` is not a valid polyphonic event.
      """
      if not isinstance(event, PolyphonicEvent):
          raise ValueError("Invalid polyphonic event: %s" % event)
      self._events.append(event)
  
imports: from __future__ import division
  import collections
  import copy
  from magenta.pipelines import statistics
  from note_seq import constants
  from note_seq import events_lib
  from note_seq import sequences_lib
  from note_seq.protobuf import music_pb2
  from six.moves import range
  import tensorflow.compat.v1
label_desc: Use image node_id 8 for calling the PolyphonicSequence obj's underlying member method code with example usage: obj.append(event) without return types