hat is available for this
class.  In MusicXML it is 6.

Currently, this method just iterates over the spanners of this class
and counts the number from 1-6 and then recycles numbers.  It does
not check whether more than 6 overlapping spanners of the same type
exist, nor does it reset the count to 1 after all spanners of that
class have been closed.  The example below demonstrates that the
position of the contents of the spanner have no bearing on
its idLocal (since we don't even put anything into the spanners).


>>> su1 = spanner.Slur()
>>> su2 = layout.StaffGroup()
>>> su3 = spanner.Slur()
>>> sb = spanner.SpannerBundle()
>>> sb.append(su1)
>>> sb.append(su2)
>>> sb.append(su3)
>>> [sp.idLocal for sp in sb.getByClass(spanner.Slur)]
[None, None]
>>> sb.setIdLocalByClass('Slur')
>>> [sp.idLocal for sp in sb.getByClass(spanner.Slur)]
[1, 2]
é