'Given either a dictionary or a `ConfigSource` object, return
a `ConfigSource` object. This lets a function accept either type
of object as an argument.'

@classmethod
def of(cls, value):

    if isinstance(value, ConfigSource):
        return value
    elif isinstance(value, dict):
        return ConfigSource(value)
    else:
        raise TypeError(u'source    value    must    be    a    dict')
