code: def amplifier_gain(self, channels=None):
          
          # Check default
          if channels is None:
              channels = self._channels
  
          # Get numerical indices of channels
          channels = self._name_to_index(channels)
  
          # Get detector type of the specified channels
          if hasattr(channels, '__iter__') \
                  and not isinstance(channels, six.string_types):
              return [self._amplifier_gain[ch] for ch in channels]
          else:
              return self._amplifier_gain[channels]
docs: Get the amplifier gain used for the specified channel(s).
  
          The amplifier gain for channel "n" is extracted from the $PnG
          parameter, if available.
  
          Parameters
          ----------
          channels : int, str, list of int, list of str
              Channel(s) for which to get the amplifier gain. If None,
              return a list with the amplifier gain of all channels, in the
              order of ``FCSData.channels``.
  
          Return
          ------
          float or list of float
              The amplifier gain of the specified channel(s). If no
              information about the amplifier gain is found for a channel,
              return None.