Print a vertical line and the rank number, to aid debugging.
*/
-MAKE_SCHEME_CALLBACK(Paper_column,brew_molecule,1);
+MAKE_SCHEME_CALLBACK(Paper_column,print,1);
SCM
-Paper_column::brew_molecule (SCM p)
+Paper_column::print (SCM p)
{
Grob *me = unsmob_grob (p);