def postinit(self, value, conversion=None, format_spec=None):
self.value = value<EOL>self.conversion = conversion<EOL>self.format_spec = format_spec<EOL>
Do some setup after initialisation.

        :param value: The value to be formatted into the string.
        :type value: NodeNG

        :param conversion: The type of formatting to be applied to the value.
        :type conversion: int or None

        :param format_spec: The formatting to be applied to the value.
        :type format_spec: JoinedStr or None