docs: def experiments_fmri_delete(self, experiment_id):
          """Delete fMRI data object associated with given experiment.
  
          Raises ValueError if an attempt is made to delete a read-only resource.
  
          Parameters
          ----------
          experiment_id : string
              Unique experiment identifier
  
          Returns
          -------
          FMRIDataHandle
              Handle for deleted data object or None if experiment is unknown or
              has no fMRI data object associated with it
          """
          # Get experiment fMRI to ensure that it exists
          fmri = self.experiments_fmri_get(experiment_id)
          if fmri is None:
              return None
          # Delete reference fMRI data object and set reference in experiment to
          # None. If the result of delete fMRI object is None we return None.
          # Alternatively, throw an exception to signal invalid database state.
          fmri = self.funcdata.delete_object(fmri.identifier)
          if not fmri is None:
              self.experiments.update_fmri_data(experiment_id, None)
          return funcdata.FMRIDataHandle(fmri, experiment_id)