>>> from enthought.traits.api import HasTraits, Trait
>>> from validator import bounded_string
>>>
>>> bounded_string.info = 'a string no longer than 50 characters'
>>> class DatabaseRecord(HasTraits):
...   part_desc = Trait(None, None, bounded_string)
...
>>> sprocket = DatabaseRecord()
>>> sprocket.part_desc = 0

Traceback (most recent call last):
  File "<pyshell#29>", line 1, in -toplevel-
    sprocket.part_desc = 0
  File "c:\wrk\src\lib\enthought\traits\trait_handlers.py", line 
90, in error
    raise TraitError, ( object, name, self.info(), value )
TraitError: The 'part_desc' trait of a DatabaseRecord instance 
must be a string no longer than 50 characters or None, but a 
value of 0 was specified.
