Python-сообщество

>>> def mul3(obj):
...     return obj * 3
... 
>>> mul3(1)
3
>>> 
>>> mul3('a')
'aaa'
>>> 
>>> mul3([1, 2, 3])
[1, 2, 3, 1, 2, 3, 1, 2, 3]
>>> 
>>> mul3(mul3('abc'))
'abcabcabcabcabcabcabcabcabc'
>>> 
>>> mul3([mul3('abc')])
['abcabcabc', 'abcabcabc', 'abcabcabc']
>>> 
>>> mul3([tuple(mul3([mul3('abc'), mul3(mul3(3))]))])
[('abcabcabc', 27, 'abcabcabc', 27, 'abcabcabc', 27), ('abcabcabc', 27, 'abcabcabc', 27, 'abcabcabc', 27), ('abcabcabc', 27, 'abcabcabc', 27, 'abcabcabc', 27)]
>>> 
>>> mul3('a') * mul3(2)
'aaaaaaaaaaaaaaaaaa'
>>> 
>>> mul3('a') + mul3('bb')
'aaabbbbbb'
>>>

>>> def mul3(obj):
...     obj.x *= 3
...     return obj
... 
>>> class A:
...     x = 1
... 
>>> a = mul3(A())
>>> 
>>> mul3(1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in mul3
AttributeError: 'int' object has no attribute 'x'
>>> 
>>> mul3('a')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in mul3
AttributeError: 'str' object has no attribute 'x'
>>> 
>>> mul3([1, 2, 3])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in mul3
AttributeError: 'list' object has no attribute 'x'
>>> 
>>> mul3(A()) + mul3(A())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'A' and 'A'
>>> 
>>> mul3(A()) * mul3(A())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for *: 'A' and 'A'
>>>