docs: def generate_file_name(self):
          """generate a suitable file name for the experiment"""
          if not self.project:
              raise UnderDefined("project name not given")
  
          out_data_dir = prms.Paths.outdatadir
          project_dir = os.path.join(out_data_dir, self.project)
          file_name = "cellpy_batch_%s.json" % self.name
          self.file_name = os.path.join(project_dir, file_name)