code: def set(x, y, r, g, b)
  			check_coords(x, y)
  			self[x, y] = Color.new(r, g, b)
  		end
docs: Set given pixel identified by +x+, +y+ to +r+, +g+, +b+
  
   See <tt>[]=</tt> for a method that takes +Color+ instance instead
   of individual components.
  
   You still have to call +show+ to make the changes visible.