thin directory 'where'.

        'where' is the root directory which will be searched.
        It should be supplied as a "cross-platform" (i.e. URL-style) path;
        it will be converted to the appropriate local path syntax.

        'exclude' is a sequence of names to exclude; '*' can be used
        as a wildcard in the names.
        When finding packages, 'foo.*' will exclude all subpackages of 'foo'
        (but not 'foo' itself).

        'include' is a sequence of names to include.
        If it's specified, only the named items will be included.
        If it's not specified, all found items will be included.
        'include' can contain shell style wildcard patterns just like
        'exclude'.
        )