Denis535

namespace ConsoleApp;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.VisualStudio.Threading;

class Program {

Denis535

public class HierarchicalStringBuilder {
    private struct Node {
        public int Level { get; }
        public string Prefix { get; }
        public string Text { get; }
        public Node(int level, string prefix, string text) {
            (Level, Prefix, Text) = (level, prefix, text);
        }
        public override string ToString() {
            return string.Format( "Node: {0}, {1}", Level, Text );

Denis535

namespace System.Diagnostics.CodeAnalysis {

    // Input:  field, property, argument
    // Output: field, property, argument, result

    // AllowNull            - Null input is allowed
    // DisallowNull         - Null input is disallowed

    // MaybeNull            - Output may be null
    // MaybeNull/When       - Output may be null (when result == true/false)