Getting error while installing oncall (pip install -e '.[dev]')

Hi Team,

We are trying oncall in our infrastructure, I am getting the below error while installing "pip install -e '.[dev]'". Please help to fix it.

(oncall) root@iris2:~/oncall# python --version
Python 2.7.6

(oncall) root@iris2:~/oncall# pip --version
pip 18.0 from /root/oncall/local/lib/python2.7/site-packages/pip (python 2.7)

Complete output from command python setup.py egg_info:
Traceback (most recent call last):
File "", line 1, in
File "/tmp/pip-install-ptgnVW/tornado/setup.py", line 146, in
raise ImportError("Tornado requires an up-to-date SSL module. This means "
ImportError: Tornado requires an up-to-date SSL module. This means Python 2.7.9+ or 3.4+ (although some distributions have backported the necessary changes to older versions).

Reproduce `pip install -e '.[dev]'` using the reported Python 2.7.6 and pip 18.0 versions, then inspect the dependency installation output around `tornado/setup.py`. Compare the project's supported Python versions and dependency requirements; done means the documented installation command completes successfully or the incompatibility is clearly reported.

Written by the indexing model from the issue text.