<PackageReference Include="Newtonsoft.Json" Version="6.0.7" />

Lookup<TKey, TElement>

sealed class Lookup<TKey, TElement> : ILookup<TKey, TElement>, IEnumerable<IGrouping<TKey, TElement>>, IEnumerable
Represents a collection of keys each mapped to one or more values.
public int Count { get; }

Gets the number of key/value collection pairs in the Lookup<T, U>.

public IEnumerable<TElement> this[TKey key] { get; }

Gets the collection of values indexed by the specified key.

public IEnumerable<TResult> ApplyResultSelector<TResult>(Func<TKey, IEnumerable<TElement>, TResult> resultSelector)

Applies a transform function to each key and its associated values and returns the results.

public bool Contains(TKey key)

Determines whether a specified key is in the Lookup<T, U>.

public IEnumerator<IGrouping<TKey, TElement>> GetEnumerator()

Returns a generic enumerator that iterates through the Lookup<T, U>.