code: def get_channel_unit(self, name=None, group=None, index=None):
          
          gp_nr, ch_nr = self._validate_channel_selection(name, group, index)
  
          grp = self.groups[gp_nr]
  
          channel = grp.channels[ch_nr]
  
          conversion = channel.conversion
  
          unit = conversion and conversion.unit or channel.unit or ""
  
          return unit
docs: Gets channel unit.
  
          Channel can be specified in two ways:
  
          * using the first positional argument *name*
  
              * if there are multiple occurrences for this channel then the
                *group* and *index* arguments can be used to select a specific
                group.
              * if there are multiple occurrences for this channel and either the
                *group* or *index* arguments is None then a warning is issued
  
          * using the group number (keyword argument *group*) and the channel
            number (keyword argument *index*). Use *info* method for group and
            channel numbers
  
  
          If the *raster* keyword argument is not *None* the output is
          interpolated accordingly.
  
          Parameters
          ----------
          name : string
              name of channel
          group : int
              0-based group index
          index : int
              0-based channel index
  
          Returns
          -------
          unit : str
              found channel unit