SyntaxWarning: "is" with a literal. Did you mean "=="?

armarx-package prints this if called with armarx-package.

/home/tobiasjacob/code/armarx/ArmarXCore/etc/python/armarx_package/Template.py:73: SyntaxWarning: "is" with a literal. Did you mean "=="?
  if "VERBOSE" in environ.keys() and environ["VERBOSE"] is "1":