code: def get_xy_name(self, yidx, xidx=0):
          
          assert isinstance(xidx, int)
          if isinstance(yidx, int):
              yidx = [yidx]
  
          uname = ['Time [s]'] + self.uname
          fname = ['$Time\\ [s]$'] + self.fname
  
          xname = [list(), list()]
          yname = [list(), list()]
  
          xname[0] = uname[xidx]
          xname[1] = fname[xidx]
  
          yname[0] = [uname[i] for i in yidx]
          yname[1] = [fname[i] for i in yidx]
  
          return xname, yname
docs: Return variable names for the given indices
  
          :param yidx:
          :param xidx:
          :return: