Return a value from the container or None if the value is not set.

        :param key: a string using dotted notation for nested dictionary
                    lookups

def get(self, key):
        """Return a value from the container or None if the value is not set.

        :param key: a string using dotted notation for nested dictionary
                    lookups
        """
        self.inspect_if_not_inspected()

        def get_value(dictionary, key):
            return (dictionary or {}).get(key)

        return reduce(get_value, key.split('.'), self.dictionary)