The relax data store singleton method 'add()' has been deleted as the method required the first
argument to be the singleton instance. Instead the functionality has been shifted into the
generic_fns.pipes.create() function. The unit tests have been modified for the new setup.
All references to 'run' in the file 'test_suite/unit_tests/generic_fns/test_pipes.py' have been
replaced with 'pipe'.
