Accessing elements in a list from a playbook

I’m not sure if this is the right mailing list group to ask general questions or if this is just for developers. If not, then let me know what the correct group is. Anyway, my question is I’m trying to update some old playbooks to conform to the newer syntax for variables ie. {{ foo }} instead of $foo. In many of these playbooks I pass in a variable from a master includes playbook to sub-playbooks and I then use that variable as a positional parameter to access a specific element in a list. So instead of writing ${servername[0]} I do ${servername[$iteration]} where iteration is my position in the list I want to access in my vars file. I may just rewrite the whole bunch of playbooks to accomplish my task differently but for now I’d just like to update my playbooks to use the newer standard. (Since updating Ansible last time I get the warning that the old variable style will not be supported soon) I don’t want to upgrade and find out all my playbooks don’t work anymore.

Any I’ve been trying to figure out how to change the ${servername[$iteration]} to me the new standards and just can’t figure it out. Does anybody know how to do this now?