'Lesson 2 Matching sets of characters
A set of characters is defined using the metacharacters [ and ]. Everything between them is part of the set and
any one of the set members must match (but not all).'

def test_matching_set_character(self):

    string = (((((((('sales.xlx\n' + 'sales1.xls\n') + 'orders3.xls\n') + 'apac1.xls\n') + 'sales2.xls\n') + 'na1.xls\n') + 'na2.xls\n') + 'sa1.xls\n') + 'ca1.xls')
    change_this_search_string = '[nsc]a[2-9].xls'
    self.assertEquals(len(re.findall(change_this_search_string, string)), 3)
