<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_value(self, class_name, attr, default_value=None, state='normal', base_name='View'):
 """Get a single style attribute value for the given class. """

        styles = self.get_dict_for_class(class_name, state, base_name)
        try:
            return styles[attr]
        except KeyError:
            return default_value