def magnitude(self, value=None):
        mag = self.__mag()
        if value is None: return mag
        if zero(mag):
            raise ValueError, 'Zero-magnitude vector cannot be scaled.'
        v = self.__class__(self)
        v.__imul__(value / mag)
        v._l = value
        return v
Find the magnitude (spatial length) of this vector.
dataset/ETHPy150Open hhatto/autopep8/test/vectors_example.py/V.magnitude