Question

Is tuple and list compatible? Normally, you can not add a tuple with a list. e.g.
>>> a = [1,2]
>>> b = (1,2)
>>> c = a + b
>>> TypeError!

But in this class, a tuple + a list = a list! ???
class inteSet:
def __init__(self, *number):
self.lst = [1]
print type(number)
self.lst += number
print type(self.lst)

def insert(self,e):
self.lst.append(e)
print self.lst

newNum = inteSet(23, 34)
newNum.insert(3)

Answer 1

the += operator must iterate over the (right side) expression if it is a sequence
- behavior similar to extend
```
>>> a = [1]
>>> b = (1,2)
>>> a += b
>>> a
[1, 1, 2]
>>> a = a + b

Traceback (most recent call last):
File "<pyshell#77>", line 1, in <module>
a = a + b
TypeError: can only concatenate list (not "tuple") to list
>>> a.append(b)
>>> a
[1, 1, 2, (1, 2)]
>>> a.extend(b)
>>> a
[1, 1, 2, (1, 2), 1, 2]
>>>
```

Answer 2

You are right. Looks like 'self +=' is more than just 'self = self +'

same thing with the operator .iadd - similar to a.externd(b).
>>> import operator
>>> z = operator.iadd(a, b)