def uuids(self):
for f in self._seq:<EOL><INDENT>if isinstance(f, File):<EOL><INDENT>yield f.uuid<EOL><DEDENT>elif isinstance(f, six.string_types):<EOL><INDENT>yield f<EOL><DEDENT>else:<EOL><INDENT>raise ValueError(<EOL>'<STR_LIT>'.format(type(f)))<EOL><DEDENT><DEDENT>
Extract uuid from each item of specified ``seq``.