Return the default value for the parameter. If here is no default value, return None

def get_default_value(self):
        """
        Return the default value for the parameter. If here is no default value, return None
        """
        if ('default_value' in self.attributes and
                bool(self.attributes['default_value'].strip())):
            return self.attributes['default_value']
        else:
            return None