Question: 'Do Nothing'
I have similar situation as described in [Do Nothing](https://doc.kaitai.io/user_guide.html#do-nothing) in the documentation.

~~~yml
seq:
  - id: rec_type
    type: u4
  - id: body
    type:
      switch-on: rec_type
      cases:
        1: rec_type_1
        2: rec_type_2
        3: dummy # <= must ignore rec_type=3!
        _: rec_type_others
~~~


where I want to have the `body` of given type only if the `rec_type` is of certain cases only. all others should be neglected
there are hundreds of records in a single file, Something similar to below

~~~yml
seq:
  - id: event
    type: t_event_type
    repeat: eos

types:
  t_event_type:
    seq:
      - id: event_length
        type: u2
      - id: event_type
        type: u2
      - id: event_data                              <--- this is where body comes with certain event types, ignoring other types
        size: event_length - 7
~~~

now if I introduce `siwtch-on` like above and defining the types for bodies of only records I needed.
similar to the documentation, how does kaitai know how many bytes to ignore to goto the next record? I understand how kaitai know when to start next record if we have given the data type in a squence, but if we define dummy_x types as below, how does it know the ignored event's body is over and parse the next event?

~~~yml
ypes:
  # One can use empty JSON object syntax to avoid specifying any of
  # `seq`, `instances`, etc, sections.
  dummy_1: {}
  # One can use explicit doc to note that there's nothing there.
  dummy_2:
    doc: This type is intentionally left blank.
  # One can use empty `seq` or `instances` or `types` section, any
  # other empty sections, or any combination of thereof.
  dummy_3:
    seq: []
    instances: {}
    types: {}
  # One can use a very explicit notion of the fact that we want to parse 0 bytes.
  dummy_4:
    seq:
      - id: no_value
        size: 0
~~~


