AngleSharp by Florian Rappl

<PackageReference Include="AngleSharp" Version="0.2.1" />

 DOMTokenList

public sealed class DOMTokenList : DOMCollection, IEnumerable<string>, IEnumerable
Represents a list of DOMTokens.
public string this[int index] { get; }

Gets an item in the list by its index.

public int Length { get; }

Gets the number of tokens.

public DOMTokenList()

Creates a new list of tokens.

public DOMTokenList Add(string token)

Adds token to the underlying string.

public bool Contains(string token)

Returns true if the underlying string contains token, otherwise false.

public IEnumerator<string> GetEnumerator()

public DOMTokenList Remove(string token)

Remove token from the underlying string.

public bool Toggle(string token)

Removes token from string and returns false. If token doesn't exist it's added and the function returns true.