Change required modules.

        Reload modules given in the value.

        :param list value: new modules to use.

def modules(self, value):
        """Change required modules.

        Reload modules given in the value.

        :param list value: new modules to use."""

        modules = [module.__name__ for module in self.loadmodules(value)]

        self._modules = [
            module for module in self._modules + modules
            if module not in self._modules
        ]