gistfile1.txt

---    
  - hosts: localhost
    connection: local
       
    vars:
      var1: false                                                                                                                                                                                                  
      var2: '{{ var1 }}'
       
    tasks:
    - debug: var=var1
    - debug: var=var2

gistfile2.txt

PLAY [localhost] ************************************************************** 

GATHERING FACTS *************************************************************** 
ok: [localhost]

TASK: [debug var=var1] ******************************************************** 
ok: [localhost] => {
    "var": {
        "var1": "False"
    }
}

TASK: [debug var=var2] ******************************************************** 
ok: [localhost] => {
    "var": {
        "var2": "False"
    }
}