let disp_help () = disp_welcome () ; pl "\nusage: sis [options]\n -p <str> : validation predicate\n -t <str> : validation transform\n -rp <str> : rejection predicate\n -rt <str> : rejection transform\n -o <str> : select an opacity. Values are\n Opaque/Residues/Transparent\n --no-blank : don't print blank lines\n --help : print this help and exit\n --help <str> : print the documentation for a function\n --predicates : print the list of all valid predicates\n --transforms : print the list of all valid transforms\n --funs : print the list of all valid functions\n --docu : print the whole documentation of all functions\n \n"