Add a new process to the registry.

        :param process: A callable (either plain function or object
            implementing __calll).
        :param name: The name of the executable to match. If not given
            it must be provided as 'name' attribute of the given `process`.
            callable.

def add(self, process, name=None):
        """Add a new process to the registry.

        :param process: A callable (either plain function or object
            implementing __calll).
        :param name: The name of the executable to match. If not given
            it must be provided as 'name' attribute of the given `process`.
            callable.
        """
        name = name or process.name
        assert name, "No executable name given."""
        self._registry[name] = process