def __init__(self, groups=None):
        super(GroupedRequirements, self).__init__(NamedRequirements)
        self.groups = groups or self.default_groups
        self.filename = None
        self.create_default_groups()
def foam_arch(self):
        if not self._foam_arch:
            self._foam_arch = OpenfoamOrgArch(self.spec, **self.config)
        return self._foam_arch