docs: def collect_gdf(self):
          """
          Collect the gdf-files from network sim in folder `spike_output_path`
          into sqlite database, using the GDF-class.
          
          
          Parameters
          ----------
          None
          
          
          Returns
          -------
          None
          
          """
          # Resync
          COMM.Barrier()
  
          # Raise Exception if there are no gdf files to be read
          if len(glob.glob(os.path.join(self.spike_output_path,
                                        self.label + '*.'+ self.ext))) == 0:
              raise Exception('path to files contain no gdf-files!')
  
          #create in-memory databases of spikes
          if not hasattr(self, 'dbs'):
              self.dbs = {}
          
          for X in self.X:
              db = GDF(os.path.join(self.dbname),
                       debug=True, new_db=True)
              db.create(re=os.path.join(self.spike_output_path,
                                        '{0}*{1}*{2}'.format(self.label, X,
                                                             self.ext)),
                        index=True)
              self.dbs.update({
                      X : db
                  })
        
          COMM.Barrier()