Example that removes the need for regions

Example.cs

interface IRepository<TEntity>
{
	TEntity FindOne(Guid id);
	void Save(TEntity entity);
}

interface IUsersRepository : IRepository<User>
{
	User FindOneByUsername(string username);
}

interface IGroupsRepository : IRepository<Group>
{
	Group FindOneByName(string name);
}

class Database : IUsersRepository, IGroupsRepository
{
	void IUsersRepository.FindOne(Guid id)
	{
		return FindOne<User>(id);
	}

	void IUsersRepository.Save(User entity)
	{
		Save(entity);
	}

	User IUsersRepository.FindOneByUsername(string username)
	{
		throw new NotImplementedException();
	}

	void IGroupsRepository.FindOne(Guid id)
	{
		return FindOne<Group>(id);
	}

	void IGroupsRepository.Save(Group entity)
	{
		Save(entity);
	}

	void IGroupsRepository.FindOneByName(string name)
	{
		throw new NotImplementedException();
	}

	private TEntity FindOne<TEntity>(Guid id)
	{
		throw new NotImplementedException();
	}

	private void Save<TEntity>(TEntity entity)
	{
		throw new NotImplementedException();
	}
}