'Initializes a ConfigSection
@param members a dictionary whose keys are the attributes by which
the members are accessed. For example:
members=dict(FOO=Config(...))
means that you will access this configuration as
section.FOO.get()'

def __init__(self, key=_ANONYMOUS, members=None, **kwargs):

    super(ConfigSection, self).__init__(key, default={}, **kwargs)
    self.members = (members or {})
    for member in members.itervalues():
        assert (member.key is not _ANONYMOUS)
