A signal will be provided to a handler iff ALL of the following are true:

  1. Signal call is allowed by compile-time filters
  2. Signal call is allowed by runtime      filters
  3. Handler     is allowed by runtime      filters

  4. Signal call middleware does not suppress the signal (return nil)
  5. Handler     middleware does not suppress the signal (return nil)

For more info:

  - On call    filters, see: `help:filters`  docstring
  - On handler filters, see: `help:handlers` docstring
  - On signal flow,     see: Ref. <https://tinyurl.com/telemere-signal-flowchart>

If anything is unclear, please ping me (@ptaoussanis) so that I can
improve these docs!
