code: def event_shape(self) -> Tuple:
      return self.distr_outputs[0].event_shape
  
imports: from typing import List, Optional, Tuple
  import mxnet
  import numpy
  from mxnet import gluon
  from gluonts.core.component import validated
  from gluonts.mx import Tensor
  from .distribution import MAX_SUPPORT_VAL, Distribution, _expand_param, _index_tensor, getF
  from .distribution_output import DistributionOutput
label_desc: Use image node_id 4 for calling the MixtureDistributionOutput obj's underlying member method code with example usage: obj.event_shape() and returns: self