code: def get_max_muO2(self, min_voltage=None, max_voltage=None):
          
          data = []
          for pair in self._select_in_voltage_range(min_voltage, max_voltage):
              if pair.muO2_discharge is not None:
                  data.extend([d['chempot'] for d in pair.muO2_discharge])
              if pair.muO2_charge is not None:
                  data.extend([d['chempot'] for d in pair.muO2_discharge])
          return max(data) if len(data) > 0 else None
docs: Maximum critical oxygen chemical potential along path.
  
          Args:
              min_voltage: The minimum allowable voltage.
              max_voltage: The maximum allowable voltage.
  
          Returns:
              Maximum critical oxygen chemical of all compounds along the
              insertion path (a subset of the path can be chosen by the optional
              arguments).