installing ansbile - ImportError: No module named ansible.constants

I downloaded the ansible latest from

https://releases.ansible.com/ansible/

untarred and ran ansible, getting the below error

Traceback (most recent call last):
File “./ansible”, line 43, in
import ansible.constants as C

did you source hacking/env-setup first?

You can’t just untar and run. If you want to run from source, you will need to following the instructions from http://docs.ansible.com/ansible/intro_installation.html#running-from-source

there is no hacking/env-setup

there are only these files under hacking dir

dump_playbook_attributes.py module_formatter.py templates

I dont want to run from source. I dont know which package in the releases is source and which is just binary.

please point me to a package that i need if i want to just untar and get going. thanks.