>>> def x(depth):
... y(depth)
>>> def y(depth):
- ... print caller_name(depth)
+ ... print(caller_name(depth))
>>> x(1)
y
>>> x(2)
>>> def y():
... z()
>>> def z():
- ... print list(caller_names())
+ ... print(list(caller_names()))
>>> x() # doctest: +ELLIPSIS
['z', 'y', 'x', ...]
>>> y() # doctest: +ELLIPSIS