presto-main/src/main/java/io/prestosql/sql/planner/optimizations/SymbolMapper.java/SymbolMapper/rewriteSymbolReference
class SymbolMapper:    public Expression map(Expression value)
    {
        return ExpressionTreeRewriter.rewriteWith(new ExpressionRewriter<Void>()
        {
            @Override
            public Expression rewriteSymbolReference(SymbolReference node, Void context, ExpressionTreeRewriter<Void> treeRewriter)
            {
                Symbol canonical = map(Symbol.from(node));
                return canonical.toSymbolReference();
            }
        }, value);
    }