What is xrange?

[nilamo]

It's just like range(), except it only generates numbers as you ask for them (instead of all at once).  If you wanted to see what it looks like in practice, here's a bad version I just made up:

>>> class xrange:
...   def __init__(self, min=0, max=None, step=1):
...     if max is None:
...       max = min
...       min = 0
...     self.max = max
...     self.step = step
...     self.current = min
...   def __iter__(self):
...     return self
...   def __next__(self):
...     value = self.current
...     self.current += self.step
...     if self.step > 0:
...       if value >= self.max:
...         raise StopIteration()
...     else:
...       if value <= self.max:
...         raise StopIteration()
...     return value
...
>>> for i in xrange(5):
...   print(i)
...
0
1
2
3
4
>>> for i in xrange(2, 12, 3):
...   print(i)
...
2
5
8
11