1/build_RC { 2 pop 3 size 4 div /side exch def 4 currentpoint 5 newpath 6 moveto 7 0 side 1.5 mul rmoveto 8 0 side rlineto 9 side 2.5 mul 0 rlineto 10 0 side neg rlineto 11 closepath 12 fill 13} def 14