The default variable {{ var.value.my_var }} don't exists!

[Wang Yajun]

Hi

it seems that the default variable {{ var.value.my_var }} described in this
wiki <https://pythonhosted.org/airflow/code.html#macros> don't exists!

I use it like below:

cmd = "{{  var.value.RS_ENV }}"


my airflow version: 1.7.1.3