##
11.4.6 HTTPPasswordMgr Objects

These methods are available on `HTTPPasswordMgr` and `HTTPPasswordMgrWithDefaultRealm` objects.

`add_password`(realm, uri, user, passwd)
  uri can be either a single URI, or a sequene of URIs. realm, user and passwd must be strings. This causes `(user, passwd)` to be used as authentication tokens when authentication for realm and a super-URI of any of the given URIs is given.

`find_user_password`(realm, authuri)
  Get user/password for given realm and URI, if any. This method will return `(None, None)` if there is no matching user/password.

  For `HTTPPasswordMgrWithDefaultRealm` objects, the realm `None` will be searched if the given realm has no matching user/password.