This is the environment implementation of
        :meth:`BaseGroups.findGlyph`. **glyphName** will be
        an :ref:`type-string`.

        Subclasses may override this method.

def _findGlyph(self, glyphName):
        """
        This is the environment implementation of
        :meth:`BaseGroups.findGlyph`. **glyphName** will be
        an :ref:`type-string`.

        Subclasses may override this method.
        """
        found = []
        for key, groupList in self.items():
            if glyphName in groupList:
                found.append(key)
        return found