This is MetaPost, Version 0.993 (Web2C 7.5.6) (mem=mpost 2008.5.8)  9 MAY 2008 00:18
**successors.mp
(successors.mp (chord.mp (/usr/share/texmf-texlive/metapost/base/boxes.mp))
[1] )
1 output file written: successors.1