How to use the statistics.varf3d_MPI function in statistics

sumvol += volref
			set_filter_parameters_from_adjusted_fsc(Tracker["constants"]["total_stack"],ngroup[iref],Tracker)
			if myid==main_node:
				log.add("%d reference low pass filter is %f  %f  %d"%(iref,Tracker["lowpass"],Tracker["falloff"],ngroup[iref]))
			refdata= [None]*4
			refdata[0] = volref
			refdata[1] = Tracker
			refdata[2] = None
			refdata[3] = None
			volref = user_func(refdata)
			if myid == main_node:
				volref.write_image(os.path.join(outdir, "volf%04d.hdf"%( total_iter)), iref)
			del volref
		if runtype=="REFINEMENT":
			if fourvar:
				varf = varf3d_MPI(data, os.path.join(outdir, "ssnr%04d"%total_iter), None,sumvol,last_ring, 1.0, 1, CTF, 1, sym, myid)
				if myid == main_node:   
					varf = 1.0/varf
					varf.write_image( os.path.join(outdir,"varf%04d.hdf"%total_iter) )                            		
		#  here we  write header info
		mpi_barrier(MPI_COMM_WORLD)
		#start_time = time()
		if runtype=="REFINEMENT":
			par_str = ['xform.projection', 'ID', 'group']
		else:
			par_str = ['group', 'ID' ]
	        #if myid == main_node:
		#	from utilities import file_type
	        #	if file_type(stack) == "bdb":
	        #		from utilities import recv_attr_dict_bdb
	        #		recv_attr_dict_bdb(main_node, stack, data, par_str, image_start, image_end, number_of_proc)
	        #	else:

if debug:
		finfo.write( "Image_start, image_end: %d %d\n" %(image_start, image_end) )
		finfo.flush()
	start_time = time()
	if myid == main_node:
		log.add( "Time to read data: %d\n" % (time()-start_time) );start_time = time()
	#  Initialize Particle ID and set group number to non-existant -1
	assignment = [-1]*len(data)
 	for im in xrange(len(data)):
		data[im].set_attr_dict({'ID':list_of_particles[im], 'group':-1})
	if fourvar:
		from reconstruction import rec3D_MPI
		from statistics     import varf3d_MPI
		#  Compute Fourier variance
		vol, fscc = rec3D_two_chunks_MPI(data,snr,sym,fscmask,os.path.join(outdir, "resolution0000"), myid, main_node, finfo=frec, npad=npad)
		varf = varf3d_MPI(data, os.path.join(outdir, "ssnr0000"), None, vol, last_ring, 1.0, 1, CTF, 1, sym, myid)
		if myid == main_node:   
			varf = 1.0/varf
			varf.write_image( os.path.join(outdir,"varf0000.hdf") )
	else:
		varf = None
	refdata        =[None]*4
	for  iref in xrange(numref):
		set_filter_parameters_from_adjusted_fsc(Tracker["constants"]["total_stack"],Tracker["number_of_ref_class"][iref],Tracker)
		refdata[0] = ref_list[iref]
		refdata[1] = Tracker
		refdata[2] = 0
		refdata[3] = None
		volref = user_func(refdata)
		if myid ==main_node:
			log.add("%d reference low pass filter is %f  %f    %d"%(iref, Tracker["lowpass"], Tracker["falloff"],Tracker["number_of_ref_class"][iref]))
			ref_list[iref].write_image(os.path.join(outdir, "volf0000.hdf"), iref)

if( type(stack) is types.StringType ):
			data[im] = get_im(stack, list_of_particles[im])
			data[im].set_attr_dict({'ID':list_of_particles[im], 'group':-1})
		else:
			data[im] = stack[list_of_particles[im]]
			#  NOTE: in case data comes in, it would have to have ID set as there is no way to tell here what was the original ordering.
			data[im].set_attr_dict({ 'group':-1})
	if(myid == 0):
		log.add( "Time to read data: %d" % (time()-start_time) );start_time = time()

	if fourvar:
		from reconstruction import rec3D_MPI
		from statistics     import varf3d_MPI
		#  Compute Fourier variance
		vol, fscc = rec3D_MPI(data, snr, sym, model_circle(last_ring, nx, nx, nx), os.path.join(outdir, "resolution0000"), myid, main_node, finfo=frec, npad=npad)
		varf = varf3d_MPI(data, os.path.join(outdir, "ssnr0000"), None, vol, last_ring, 1.0, 1, CTF, 1, sym, myid)
		if myid == main_node:   
			varf = 1.0/varf
			varf.write_image( os.path.join(outdir,"varf0000.hdf") )
	else:
		varf = None

	if myid == main_node:
		refdata = [None]*7
		for  iref in xrange(numref):
			vol = get_im(ref_vol, iref).write_image(os.path.join(outdir, "vol0000.hdf"), iref)
		refdata[0] = numref
		refdata[1] = outdir
		refdata[2] = frequency_low_pass
		refdata[3] = 0
		#refdata[4] = varf
		refdata[5] = mask3D