code: def update_fmri_data(self, identifier, fmri_data_id):
          
          # Get experiment to ensure that it exists
          experiment = self.get_object(identifier)
          if experiment is None:
              return None
          # Update fmri_data property and replace existing object with updated one
          experiment.fmri_data_id = fmri_data_id
          self.replace_object(experiment)
          # Return modified experiment
          return experiment
docs: Associate the fMRI object with the identified experiment.
  
          Parameters
          ----------
          identifier : string
              Unique experiment object identifier
          fmri_data_id : string
              Unique fMRI data object identifier
  
          Returns
          -------
          ExperimentHandle
              Returns modified experiment object or None if no experiment with
              the given identifier exists.