unsupported operand type(s) python v2.7

[ngangsia akumbo]

>>> def n():
	34 * 2

	
>>> def g():
	4 + 2

>>> def ng():
	return n() + g()

>>> ng()

Traceback (most recent call last):
  File "<pyshell#14>", line 1, in <module>
    ng()
  File "<pyshell#13>", line 2, in ng
    return n() + g()
TypeError: unsupported operand type(s) for +: 'NoneType' and 'NoneType'