def unmarshal(self, v):
        """
        Convert the value from parsed JSON structure to native python representation.

        By default this will leave the value as-is since the JSON parsing routines
        typically convert to native types. The exception may be date strings or other
        more complex types, where subclasses will override this behavior.
        """
        if self.units:
            # Note that we don't want to cast to type in this case!
            if not isinstance(v, Quantity):
                v = self.units(v)
        elif not isinstance(v, self.type):
            v = self.type(v)
        return v
Convert the value from parsed JSON structure to native python representation.

        By default this will leave the value as-is since the JSON parsing routines
        typically convert to native types. The exception may be date strings or other
        more complex types, where subclasses will override this behavior.