def _get_environ_vars(self):<EOL>
for key, val in os.environ.items():<EOL><INDENT>should_be_yielded = (<EOL>key.startswith("<STR_LIT>") and<EOL>key[<NUM_LIT:4>:].lower() not in self._ignore_env_names<EOL>)<EOL>if should_be_yielded:<EOL><INDENT>yield key[<NUM_LIT:4>:].lower(), val<EOL><DEDENT><DEDENT>
Returns a generator with all environmental vars with prefix PIP_