docs: def _load_lsm_data(self, data_var,
                         conversion_factor=1,
                         calc_4d_method=None,
                         calc_4d_dim=None,
                         time_step=None):
          """
          This extracts the LSM data from a folder of netcdf files
          """
          data = self.xd.lsm.getvar(data_var,
                                    yslice=self.yslice,
                                    xslice=self.xslice,
                                    calc_4d_method=calc_4d_method,
                                    calc_4d_dim=calc_4d_dim)
          if isinstance(time_step, datetime):
              data = data.loc[{self.lsm_time_dim: [pd.to_datetime(time_step)]}]
          elif time_step is not None:
              data = data[{self.lsm_time_dim: [time_step]}]
          data = data.fillna(0)
          data.values *= conversion_factor
          return data