docs: def increment_data(self):
          """perform the dq-dv transform"""
  
          # NOTE TO ASBJOERN: Probably insert method for "binning" instead of
          # differentiating here
          # (use self.increment_method as the variable for selecting method for)
  
          logging.debug("incrementing data")
  
          # ---- shifting to y-x ----------------------------------------
          v1, v2 = value_bounds(self.voltage_preprocessed)
          if self.voltage_resolution is not None:
              len_voltage = round(abs(v2 - v1) / self.voltage_resolution, 0)
          else:
              len_voltage = len(self.voltage_preprocessed)
  
          # ---- interpolating ------------------------------------------
          logging.debug(" - interpolating capacity(voltage)")
          f = interp1d(
              self.voltage_preprocessed,
              self.capacity_preprocessed,
              kind=self.interpolation_method
          )
  
          self.voltage_inverted = np.linspace(v1, v2, len_voltage)
          self.voltage_inverted_step = (v2 - v1) / (len_voltage - 1)
          self.capacity_inverted = f(self.voltage_inverted)
  
          if self.smoothing:
              logging.debug(" - smoothing (savgol filter window)")
              savgol_filter_window_divisor = np.amin(
                  (self.savgol_filter_window_divisor_default, len_voltage / 5)
              )
  
              savgol_filter_window_length = int(
                  len(self.voltage_inverted) / savgol_filter_window_divisor
              )
  
              if savgol_filter_window_length % 2 == 0:
                  savgol_filter_window_length -= 1
  
              self.capacity_inverted = savgol_filter(
                  self.capacity_inverted,
                  np.amax([3, savgol_filter_window_length]),
                  self.savgol_filter_window_order
              )
  
          # ---  diff --------------------
          if self.increment_method == "diff":
              logging.debug(" - diff using DIFF")
              self.incremental_capacity = np.ediff1d(self.capacity_inverted) / self.voltage_inverted_step
              self._incremental_capacity = self.incremental_capacity
              # --- need to adjust voltage ---
              self._voltage_processed = self.voltage_inverted[1:]
              self.voltage_processed = self.voltage_inverted[1:] - 0.5 * self.voltage_inverted_step  # centering
  
          elif self.increment_method == "hist":
              logging.debug(" - diff using HIST")
              # TODO: Asbjoern, maybe you can put your method here?
              raise NotImplementedError