PyCharm: DJANGO_SETTINGS_MODULE is undefined
for new commers, below is the additional info'.
where you can find the place to set DJANGO_SETTINGS_MODULE in pycharm 2019.1 is:
config -> language and frameworks -> Django's right pain.
the column just below the django project root you can cite your config file path.
and the environment variables column you can set DJANGO_SETTINGS_MODULE value.
I am using PyCharm IDE and when I run any file.py I get this error:

..raise ImportError("Settings cannot be imported, because environment
  variable %s is undefined." % ENVIRONMENT_VARIABLE) ImportError:
  Settings cannot be imported, because environment variable
  DJANGO_SETTINGS_MODULE is undefined.

How to configure DJANGO_SETTINGS_MODULE environment variable in PyCharm?