/getcolor { % ever seen anything as ugly?
        dup 8 mod 0 eq
        {0 0 0}
                {dup 8 mod 1 eq
                {0 0 1}
                        {dup 8 mod 2 eq
                        {0 1 0}
                                {dup 8 mod 3 eq
                                {0 1 1}
                                        {dup 8 mod 4 eq
                                        {1 0 0}
                                                {dup 8 mod 5 eq
                                                {1 0 1}
                                                        {dup 8 mod 6 eq
                                                        {1 1 0}
        {0.9 0.9 0.9} ifelse} ifelse} ifelse} ifelse} ifelse} ifelse} ifelse
} def

/getcoordinates {
        10
} def

/draw {
        newpath
        300 500 moveto
        dup % duplicate the top of the stack -- we need to use the number in both getcolor and getcoordinates
        getcolor setrgbcolor
        getcoordinates rlineto
        stroke
} def


0 1 100 {draw} for