code: def c_filler(self, frequency):
          '''
          Capacitance of an electrode covered in filler media (e.g., air or oil),
          normalized per unit area (i.e., units are F/mm^2).
          '''
          try:
              return np.interp(frequency,
                               self._c_filler['frequency'],
                               self._c_filler['capacitance']
              )
          except:
              pass
          return self._c_fillef c_filler(self, frequency):
          '''
          Capacitance of an electrode covered in filler media (e.g., air or oil),
          normalized per unit area (i.e., units are F/mm^2).
          '''
          try:
              return np.interp(frequency,
                               self._c_filler['frequency'],
                               self._c_filler['capacitance']
              )
          except:
              pass
          return self._c_filler
docs: Capacitance of an electrode covered in filler media (e.g., air or oil),
          normalized per unit area (i.e., units are F/mm^2).