public Task <TUser> FindByEmailAsync(string email)
{
if (String.IsNullOrEmpty(email))
{
throw new ArgumentNullException("email");
}
TUser result = IdentityUserRepository.GetUserByEmail(email) as TUser;
if (result != null)
{
return(Task.FromResult <TUser>(result));
}
return(Task.FromResult <TUser>(null));
}