def update(self, name):
if name is None:<EOL><INDENT>return<EOL><DEDENT>if name not in self._names:<EOL><INDENT>self._names[name] = len(self._names)<EOL><DEDENT>result = self._names[name] - self._current<EOL>self._current = self._names[name]<EOL>return result<EOL>
Query a name for the relative index value to be added into the
source map name field (optional 5th element).