def getSubDict(name, dict_, sep=u'_'):
    """get a sub dictionary from a serialised dictionary

    look for keys starting with name, and create a dict with it
    eg.: if "key" is looked for, {'html': 1, 'key_toto': 2, 'key_titi': 3} will return:
        {None: 1, toto: 2, titi: 3}
    @param name(unicode): name of the key
    @param dict_(dict): dictionary with the serialised list
    @param sep(unicode): separator used between name and subkey
    @return iter: iterate through the deserialised items
    """
    for k, v in dict_.iteritems():
        if k.startswith(name):
            if k == name:
                yield None, v
            elif k[len(name)] != sep:
                continue
            else:
                yield k[len(name) + 1:], v
