'introspect *data* for units converter and update the
axis.converter instance if necessary. Return *True*
if *data* is registered for unit conversion.'

def update_units(self, data):

    converter = munits.registry.get_converter(data)
    if (converter is None):
        return False
    neednew = (self.converter != converter)
    self.converter = converter
    default = self.converter.default_units(data, self)
    if ((default is not None) and (self.units is None)):
        self.set_units(default)
    if neednew:
        self._update_axisinfo()
    self.stale = True
    return True
