def _normalise(self):
        """Object is guaranteed to be a unit quaternion after calling this
        operation UNLESS the object is equivalent to Quaternion(0)
        """
        if not self.is_unit():
            n = self.norm
            if n > 0:
                self.q = self.q / n
def _normalise ( self ) : if not self . is_unit ( ) : n = self . norm if n > 0 : self . q = self . q / n
Object is guaranteed to be a unit quaternion after calling this
        operation UNLESS the object is equivalent to Quaternion(0)