unset ansible fact

[Vincent Illiano]

Hi all,  I understand that once an ansible variable is set, it cannot be unset.  I did find the medium.com article below that explains a work around.  Unfortunately, I do not understand some of the syntax.  Specifically:

"-bock: &debug"

"-bock: *debug"  

foo: !!null

Thanks for any help.  Article I'm referring to is below.

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https://medium.com/opsops/how-to-undefine-fact-in-ansible-5fff46432360 

 

---
- hosts: localhost
gather_facts: no
connection: local
tasks:
- block: &debug
- debug: var=foo
when: foo|default(None) != None
- block: *debug
vars:
foo: 2
- block: *debug
vars:
foo: !!null