code: def load_kallisto(self):
          
          kallisto_data = pd.concat(
              [self._load_single_patient_kallisto(patient) for patient in self],
              copy=False
          )
  
          if self.kallisto_ensembl_version is None:
              raise ValueError("Required a kallisto_ensembl_version but none was specified")
  
          ensembl_release = cached_release(self.kallisto_ensembl_version)
  
          kallisto_data["gene_name"] = \
              kallisto_data["target_id"].map(lambda t: ensembl_release.gene_name_of_transcript_id(t))
  
          # sum counts across genes
          kallisto_data = \
              kallisto_data.groupby(["patient_id", "gene_name"])[["est_counts"]].sum().reset_index()
  
          return kallisto_data
docs: Load Kallisto transcript quantification data for a cohort
  
          Parameters
          ----------
  
          Returns
          -------
          kallisto_data : Pandas dataframe
              Pandas dataframe with Kallisto data for all patients
              columns include patient_id, gene_name, est_counts