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.

def update_fmri_data(self, identifier, fmri_data_id):
        """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.
        """
        # 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