refactor out a pattern for adding other commands

added dance, shrug.

sequence.go

@@ -0,0 +1,11 @@
+package yay
+
+type Sequence struct {
+	Frame  int
+	Frames [][]rune
+}
+
+func (s *Sequence) Next() []rune {
+	s.Frame += 1
+	return s.Frames[s.Frame%len(s.Frames)]
+}