%!

% u v -> u+v
/vadd { 1 dict begin
  /v exch def
  /u exch def
  [ 
    u 0 get v 0 get add
    u 1 get v 1 get add
  ]
end } def

% ----------------------------------------------

/S 72 def
S dup scale
2 S div setlinewidth
4.25 5.5 translate

/U [ 0 1 ] def
/V [ 1 0 ] def
/W U V vadd def

gsave
1 0 0 setrgbcolor
newpath
0 0 moveto
U 0 get U 1 get lineto
stroke
grestore

gsave
0 1 0 setrgbcolor
newpath
0 0 moveto
V 0 get V 1 get lineto
stroke
grestore

gsave
0 0 1 setrgbcolor
newpath
0 0 moveto
W 0 get W 1 get lineto
stroke
grestore