code: def sub_variational_strategies(self):
      if not hasattr(self, "_sub_variational_strategies_memo"):
          self._sub_variational_strategies_memo = [
              module.variational_strategy
              for module in self.model.modules()
              if isinstance(module, ApproximateGP)
          ]
      return self._sub_variational_strategies_memo
  
imports: import warnings
  import torch
  from linear_operator.operators import BlockDiagLinearOperator
  from ...None import settings
  from ...distributions import MultitaskMultivariateNormal
  from ...likelihoods import Likelihood
  from ..approximate_gp import ApproximateGP
  from ..gp import GP
label_desc: Use image node_id 2 for calling the _DeepGPVariationalStrategy obj's underlying member method code with example usage: obj.sub_variational_strategies() and returns: self