'Initializes the MultiDrumOneHotEncoding.
Args:
drum_type_pitches: A Python list of the MIDI pitch values for each drum
type. If None, `DEFAULT_DRUM_TYPE_PITCHES` will be used.
ignore_unknown_drums: If True, unknown drum pitches will not be encoded.
If False, a DrumsEncodingException will be raised when unknown drum
pitches are encountered.'

def __init__(self, drum_type_pitches=None, ignore_unknown_drums=True):

    if (drum_type_pitches is None):
        drum_type_pitches = DEFAULT_DRUM_TYPE_PITCHES
    self._drum_map = dict(enumerate(drum_type_pitches))
    self._inverse_drum_map = dict(((pitch, index) for (index, pitches) in self._drum_map.items() for pitch in pitches))
    self._ignore_unknown_drums = ignore_unknown_drums
