presto-main/src/main/java/io/prestosql/sql/planner/planprinter/PlanPrinter.java/Visitor/printAssignments
class Visitor:        private void printAssignments(NodeRepresentation nodeOutput, Assignments assignments)
        {
            for (Map.Entry<Symbol, Expression> entry : assignments.getMap().entrySet()) {
                if (entry.getValue() instanceof SymbolReference && ((SymbolReference) entry.getValue()).getName().equals(entry.getKey().getName())) {
                    // skip identity assignments
                    continue;
                }
                nodeOutput.appendDetailsLine("%s := %s", entry.getKey(), unresolveFunctions(entry.getValue()));
            }
        }