How can i setup environmental variable?

Environments
1

I set my DROPBOX_TOKEN variable in both .travis.yml and in setting on travis site, but none of it dont work. This variable is used in tests, but i constantly get
KeyError: 'DROPBOX_TOKEN'
when trying to get this variable like this
ACS_TOKEN = os.environ['DROPBOX_TOKEN'].

2

When reporting a problem, please include the build log URL that shows the problem, so we can help you better.

Thanks.