.. index::
   single: None

Une fonction qui ne renvoie rien retourne None
----------------------------------------------

::

    >>> def isMoreThan10(x):
    ...     """Return (x > 10) if (x < 20)."""
    ...     if x < 20 :
    ...             return x > 10
    ... 
    >>> test = isMoreThan10(2)
    >>> test
    False
    >>> test = isMoreThan10(12)
    >>> test
    True
    >>> test = isMoreThan10(21)
    >>> test is None
    True

:Author: Jean-Philippe Camguilhem
:Contact: jean-philippe.camguilhem_at_makina-corpus.org