docs: def experiments_fmri_get(self, experiment_id):
          """Get fMRI data object that is associated with the given experiment.
  
          Parameters
          ----------
          experiment_id : string
              unique experiment identifier
  
          Returns
          -------
          FMRIDataHandle
              Handle for fMRI data object of None if (a) the experiment is unknown
              or (b) has no fMRI data object associated with it.
          """
          # Get experiment to ensure that it exists
          experiment = self.experiments_get(experiment_id)
          if experiment is None:
              return None
          # Check if experiment has fMRI data
          if experiment.fmri_data_id is None:
              return None
          # Get functional data object handle from database.
          func_data = self.funcdata.get_object(experiment.fmri_data_id)
          # Create fMRI handle from functional data handle
          return funcdata.FMRIDataHandle(func_data, experiment_id)