public static class TaskCast
{
    public static explicit operator Task<T>(T sr);
    public static Task<T> operator +(T i1, T i2);
    public static Task<T> operator -(T i1, T i2);
    public static Task<T> operator *(T i1, T i2);
    public static Task<T> operator /(T i1, T i2);
    public static Task<T> operator %(T i1, T i2);
    public static Task<T> operator -(T i);
    public static Task<bool> operator ==(T i1, T i2);