throw new ExceptionRPN("calc needs expression");
}
else if (instr.matches("^\\s*clear\\s+[\\x00-\\xff]*$") || instr.equals("clear")) {
String[] token = instr.split(" ");
if (token.length==1)
for (String s : varCollection.clear())
wy.format("remove %s\n",s);
else
for (int i=1; i<token.length; ++i)
try {
varCollection.delete(token[i]);