docs: def plot(self):
          """Show the running MOC on an all-sky map.
  
          This command requires that the Healpy and matplotlib libraries be
          available.  It plots the running MOC, which should be normalized to
          a lower order first if it would generate an excessively large pixel
          array.
  
          ::
  
              pymoctool a.moc --normalize 8 --plot
  
          It also accepts additional arguments which can be used to control
          the plot.  The 'order' option can be used instead of normalizing the
          MOC before plotting.  The 'antialias' option specifies an additional
          number of MOC orders which should be used to smooth the edges as
          plotted -- 1 or 2 is normally sufficient.  The 'file' option can
          be given to specify a file to which the plot should be saved.
  
          ::
  
              pymoctool ... --plot [order <order>] [antialias <level>] [file <filename>] ...
          """
  
          if self.moc is None:
              raise CommandError('No MOC information present for plotting')
  
          from .plot import plot_moc
  
          order = self.moc.order
          antialias = 0
          filename = None
  
          while self.params:
              if self.params[-1] == 'order':
                  self.params.pop()
                  order = int(self.params.pop())
              elif self.params[-1] == 'antialias':
                  self.params.pop()
                  antialias = int(self.params.pop())
              elif self.params[-1] == 'file':
                  self.params.pop()
                  filename = self.params.pop()
              else:
                  break
  
          plot_moc(self.moc, order=order, antialias=antialias,
                   filename=filename, projection='moll')