assert value == null : Debug.show(symbol);
assert value == null : Debug.show(symbol) + " -> " + value;
    public ClassDef insertClassDef(Symbol symbol, ClassDef classdef) {        assert symbol.isType() : Debug.show(symbol);        assert Debug.log("insert classdef: ", symbol);        Object value = classdefs.put(symbol, classdef);        assert value == null : Debug.show(symbol);        assert !templates.containsKey(symbol) : Debug.show(symbol);        return classdef;    }