'A convenience method which fetches the specified value, guaranteeing
that it is a list.
>>> a = ConfigObj()
>>> a[\'a\'] = 1
>>> a.as_list(\'a\')
[1]
>>> a[\'a\'] = (1,)
>>> a.as_list(\'a\')
[1]
>>> a[\'a\'] = [1]
>>> a.as_list(\'a\')
[1]'

def as_list(self, key):

    result = self[key]
    if isinstance(result, (tuple, list)):
        return list(result)
    return [result]
