% python
Python 2.3.4 (#1, Feb  6 2006, 10:38:46) 
[GCC 3.4.5 20051201 (Red Hat 3.4.5-2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from svn import core
>>> core.svn_invalid_revnum
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
AttributeError: 'module' object has no attribute 'svn_invalid_revnum'
>>> core.SVN_INVALID_REVNUM
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
AttributeError: 'module' object has no attribute 'SVN_INVALID_REVNUM'
>>> core.SWIG_SVN_INVALID_REVNUM
-1
>>>