types implicites et catégories
==============================

Sometimes it is a good choice to use strings as implicit types.
Some times not. Let us have some types :

::

	types = ["booltype", "stringtype", "floattype"]
	if "booltype" in types:
		print type

But we loose an information there : all these string are the same type
and not a string type.

::

	class NormalizeType(str):
		pass
	typenames = ("booltype", "stringtype", "floattype")
	globs = globals()
	for typename in typenames:
		globs[typename] = NormalizeType(typename)
	# and for example
	if type(obj) == NormalizeType:
		print type

Now we don't rely on a list, the type names present here are just for the
types's build. We rely on classes as sets.