Metronome class

1. Constructors
2. epoch
3. periodic
4. Properties
5. anchor
6. clock
7. interval
8. isBroadcast
9. first
10. hashCode
11. isEmpty
12. last
13. length
14. runtimeType
15. single
16. Methods
17. listen
18. any
19. asBroadcastStream
20. asyncExpand
21. asyncMap
22. cast
23. contains
24. distinct
25. drain
26. elementAt
27. every
28. expand
29. firstWhere
30. fold
31. forEach
32. handleError
33. join
34. lastWhere
35. map
36. noSuchMethod
37. pipe
38. reduce
39. singleWhere
40. skip
41. skipWhile
42. take
43. takeWhile
44. timeout
45. toList
46. toSet
47. toString
48. transform
49. where
50. Operators
51. operator ==