procedure main()
   v1 := vector(5,7)
   v2 := vector(2,3)
   write(v1.tostring(),"+",v2.tostring()," = ",(v1 + v2).tostring())
   write(v1.tostring(),"-",v2.tostring()," = ",(v1 - v2).tostring())
   write(v1.tostring(),"*123 = ",(v1*123).tostring())
   write(v1.tostring(),"/0.5 = ",(v1*0.5).tostring())
end

class vector(x,y)
   method tostring();return "["||x||","||y||"]"; end
   method add(v); return vector(x+v.x, y+v.y); end
   method minus(v); return vector(x-v.x, y-v.y); end
   method mult(z); return vector(x*z, y*z); end
   method div(z); return vector(x/z, y/z); end
   # The next four provide operator overloading, if enabled.
   method __add__(v); return add(v); end
   method __minus__(v); return minus(v); end
   method __mult__(z); return mult(z); end
   method __div__(z); return div(z); end
end