def addGlyph(self, glyphName, unicodes=None, instanceLocation=None, sources=None, note=None):
        """
        Calculate a new glyph and add it to this instance.
        
        *   glyphName:   The name of the glyph
        *   unicodes:   The unicode values for this glyph (optional)
        *   instanceLocation:   Location for this glyph
        *   sources:    List of sources for this glyph.
        *   note:   Note for this glyph.
        """
        self.font.newGlyph(glyphName)
        glyphObject = self.font[glyphName]
        if note is not None:
            glyphObject.note = note
            # why does this not save?
        if unicodes is not None:
            glyphObject.unicodes = unicodes
        if instanceLocation is None:
            instanceLocation = self.locationObject
        glyphMasters = []
        if sources is None:
            # glyph has no special requests, add the default sources
            for sourceName, (source, sourceLocation) in self.sources.items():
                if glyphName in self.muted['glyphs'].get(sourceName, []):
                    # this glyph in this master was muted, so do not add.
                    continue
                d = dict(   font=source,
                            location=sourceLocation,
                            glyphName=glyphName)
                glyphMasters.append(d)
        else:
            # use the glyph sources provided
            # if self.verbose and self.logger:
            #     self.logger.info("\tGlyph %s has special masters %s", glyphName, sources)
            glyphMasters = sources
        # make the glyphs
        try:
            self._calculateGlyph(glyphObject, instanceLocation, glyphMasters)
        except:
            self._failed.append(glyphName)
Calculate a new glyph and add it to this instance.
        
        *   glyphName:   The name of the glyph
        *   unicodes:   The unicode values for this glyph (optional)
        *   instanceLocation:   Location for this glyph
        *   sources:    List of sources for this glyph.
        *   note:   Note for this glyph.