Single string or list of strings in a method [duplicate]

Answer 1

A little tweak to pod2metra's answer enables the function to handle all levels of annidation:

>>> def b(*args):
...     x=[]
...     for i in args:
...             if '__iter__' in dir(i):
...                     x += b(*i)
...             else:
...                     x.append(i)
...     return x
... 
>>> b(1, (2, (3, 4)))
[1, 2, 3, 4]

Instead with the function 'a' you had:

>>> a(1, (2, (3, 4)))
[1, 2, (3, 4)]

I know it was not in the intentions of the original question, but maybe this generalization can be useful.