type
    BaseType = ref object of RootObj
        a: int

    BContainer = tuple
      b: int

    MyType = ref object of BaseType

method Yay[M](obj:BaseType):seq[M] {.base.} =
    echo "Base Yay"

method Yay[BContainer](obj:MyType):seq[BContainer] =
    echo "MyType Yay"
    return @[(10,)]

proc DoSomething[T,M](obj:var T,genType:M) =
  var yay = obj.Yay()
  echo yay


var b = new MyType
DoSomething(b, (1,))


# dstn.nim(22, 12) template/generic instantiation from here
# dstn.nim(18, 16) template/generic instantiation from here
# dstn.nim(13, 12) Error: cannot instantiate: 'BContainer'