error class

please input inputed parameter or press q

one of inputed parameterdffd
one of inputed parameterdfdf
one of inputed parameterdfdf
one of inputed parameterq
please input keys or press q

one of keysdffd
one of keysdfff
one of keyseeee
one of keysq
Traceback (most recent call last):
  File "/home/docs/IT/hater/test.py", line 38, in <module>
    y.f2('another inpuetted parameter')
  File "/home/docs/IT/hater/test.py", line 31, in f2
    for name in dictionary:
TypeError: 'NoneType' object is not iterable
>>> x.f1
{'dfdf', 'dffd'}
>>> y.f2
<bound method Test.f2 of <__main__.Test object at 0x7f318df089d0>>