docs: def get_with_rtdcbase(self, col1, col2, method, dataset,
                            viscosity=None, add_px_err=False):
          """Convenience method that extracts the metadata from RTDCBase
  
          Parameters
          ----------
          col1: str
              Name of the first feature of all isoelastics
              (e.g. isoel[0][:,0])
          col2: str
              Name of the second feature of all isoelastics
              (e.g. isoel[0][:,1])
          method: str
              The method used to compute the isoelastics
              (must be one of `VALID_METHODS`).
          dataset: dclab.rtdc_dataset.RTDCBase
              The dataset from which to obtain the metadata.
          viscosity: float or `None`
              Viscosity of the medium in mPa*s. If set to
              `None`, the flow rate of the imported data will
              be used (only do this if you do not need the
              correct values for elastic moduli).
          add_px_err: bool
              If True, add pixelation errors according to
              C. Herold (2017), https://arxiv.org/abs/1704.00572
          """
          cfg = dataset.config
          return self.get(col1=col1,
                          col2=col2,
                          method=method,
                          channel_width=cfg["setup"]["channel width"],
                          flow_rate=cfg["setup"]["flow rate"],
                          viscosity=viscosity,
                          add_px_err=add_px_err,
                          px_um=cfg["imaging"]["pixel size"])