private Operand findOperand(Statement s) {
        if(newStatements.isEmpty())
            return null;

        for(Statement n: newStatements)
            if(compareExpressions(s, n)) {
                switch (n.baseOperation) {
                    case BINATY_OPERATION:
                        BinaryOperationStatement b = (BinaryOperationStatement)n;
                        return b.lhv;
                    case UNARY_OPERATION:
                        UnaryOperationStatement u = (UnaryOperationStatement)n;
                        return u.lhv;
                }
            }//!!!иначе найти первое вхождение этого выражения в проге
        for(Statement e: expectedIn.keySet()) {
            if(compareExpressions(s, e) && !whereToReplace.get(e))
                switch (s.baseOperation) {
                    case BINATY_OPERATION:
                        BinaryOperationStatement b = (BinaryOperationStatement)e;
                        return b.lhv;
                    case UNARY_OPERATION:
                        UnaryOperationStatement u = (UnaryOperationStatement)e;
                        return u.lhv;
                }
        }
        return null;
    }