Python 2.4.1 (#2, Oct 12 2005, 01:36:32) 
[GCC 3.4.4 [FreeBSD] 20050518] on freebsd6
Type "help", "copyright", "credits" or "license" for more information.
>>> unicode('foo', 'utf99')
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
LookupError: unknown encoding: utf99
>>> unicode('foo', '.utf99')
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/local/lib/python2.4/encodings/__init__.py", line 96, in search_function
    globals(), locals(), _import_tail)
ValueError: Empty module name
>>> unicode('foo', 'utf99.')
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
LookupError: unknown encoding: utf99.