MoreEnumerableCountBy Method | 
| Name | Description | |
|---|---|---|
| CountByTSource, TKey(IEnumerableTSource, FuncTSource, TKey) | 
            Applies a key-generating function to each element of a sequence and returns a sequence of 
            unique keys and their number of occurrences in the original sequence.
              | |
| CountByTSource, TKey(IEnumerableTSource, FuncTSource, TKey, IEqualityComparerTKey) | 
            Applies a key-generating function to each element of a sequence and returns a sequence of 
            unique keys and their number of occurrences in the original sequence.
            An additional argument specifies a comparer to use for testing equivalence of keys.
              |