code: def filter_by_transcript_expression(
              self,
              transcript_expression_dict,
              min_expression_value=0.0):
          
          return self.filter_any_above_threshold(
              multi_key_fn=lambda variant: variant.transcript_ids,
              value_dict=transcript_expression_dict,
              threshold=min_expression_value)
docs: Filters variants down to those which have overlap a transcript whose
          expression value in the transcript_expression_dict argument is greater
          than min_expression_value.
  
          Parameters
          ----------
          transcript_expression_dict : dict
              Dictionary mapping Ensembl transcript IDs to expression estimates
              (either FPKM or TPM)
  
          min_expression_value : float
              Threshold above which we'll keep an effect in the result collection