>>> from minimal import Person
>>> joe = Person()
>>> print joe.weight
150.0
>>> joe.weight = 161.9     # OK to assign a float 
>>> joe.weight = 162       # OK to assign an int
>>> joe.weight = 'average' # Error to assign a string 
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "c:\wrk\src\lib\enthought\traits\trait_handlers.py", line 
89, in error
    raise TraitError, ( object, name, self.info(), 
value ) enthought.traits.trait_errors.TraitError: The 
'weight' trait of a Person instance must be a value of 
type 'float', but a value of average was specified.
