docs: def build_base(self):
          """
          create a base random land structure using the AIKIF world model
          """
          #print('Planet ' + self.name + ' has formed!')
          self.world = my_world.World( self.grid_height, self.grid_width, [' ','x','#']) 
          
          perc_land = (self.lava + (self.wind/10) + (self.rain/20) + (self.sun/10))*100
          perc_sea = (100 - perc_land)
          perc_blocked = (self.lava/10)*100
          
          #print('Calculating world : sea=', perc_sea, ' land=', perc_land, ' mountain=', perc_blocked,  )
          self.world.build_random( self.num_seeds, perc_land, perc_sea, perc_blocked)