* Original source: https://github.com/danvk/dygraphs/blob/master/src/extras/synchronizer.js
* at commit b55a71d768d2f8de62877c32b3aec9e9975ac389
*
* Original source: https://github.com/danvk/dygraphs/blob/master/src/extras/synchronizer.js
* at commit b55a71d768d2f8de62877c32b3aec9e9975ac389
*