ImmutableMemory (nuget): Immutable versions of `Memory<T>` and `Span<T>`, because `ReadOnlyMemory/Span` doesn't imply the underlying memory won't be mutated. These types either wrap known immutable objects (`String`, `ImmutableArray<T>`), or they take sole ownership of a defensive copy of the underlying memory. They then provide a non-mutating API which closely resembles `ReadOnlyMemory/Span`.
Keywords: immutable|immutability|memory|readonly-memory|span|readonly-span