docs: def calc_variances(params):
      '''
      This function calculates the variance of the sum signal and all population-resolved signals
      '''
  
      depth = params.electrodeParams['z']
  
      ############################
      ### CSD                  ###
      ############################
   
      for i, data_type in enumerate(['CSD','LFP']):
          if i % SIZE == RANK:
      
              f_out = h5py.File(os.path.join(params.savefolder, ana_params.analysis_folder,
                                             data_type + ana_params.fname_variances), 'w')
              f_out['depths']=depth
        
              for celltype in params.y:
                  f_in = h5py.File(os.path.join(params.populations_path,
                                                '%s_population_%s' % (celltype,data_type) + '.h5' ))
                  var = f_in['data'].value[:, ana_params.transient:].var(axis=1)
                  f_in.close()
                  f_out[celltype]= var
              
              f_in = h5py.File(os.path.join(params.savefolder, data_type + 'sum.h5' ))
              var= f_in['data'].value[:, ana_params.transient:].var(axis=1)
              f_in.close()
              f_out['sum']= var
          
              f_out.close()
  
      return