Update all environment variables from ``os.environ``.

        Use if ``os.environ`` was modified dynamically *after* you
        accessed an environment namespace with ``biome``.

def refresh(self):
        """Update all environment variables from ``os.environ``.

        Use if ``os.environ`` was modified dynamically *after* you
        accessed an environment namespace with ``biome``.

        """
        super(Habitat, self).update(self.get_environ(self._prefix))