code: def setLabel(self, edfsignal, label):
          
          if (edfsignal < 0 or edfsignal > self.n_channels):
              raise ChannelDoesNotExist(edfsignal)
          self.channels[edfsignal]['label'] = label
          self.update_header()
docs: Sets the label (name) of signal edfsignal ("FP1", "SaO2", etc.).
  
          Parameters
          ----------
          edfsignal : int
              signal number on which the label should be changed
          label : str
              signal label
  
          Notes
          -----
          This function is recommended for every signal and can be called only after opening a file in writemode and before the first sample write action.