@Override
	/**
	 * @see CopperASTBean#whatIsMissing()
	 */
	public Set<String> whatIsMissing()
	{
		Set<String> rv = super.whatIsMissing();
		if(lhs == null) rv.add("lhs");
		if(rhs == null) rv.add("rhs");
		if(rhsVarNames != null && rhsVarNames.size() != rhs.size()) rv.add("rhsVarNames");
		return rv;
	}