Add union op, adding 3 more US timezones

Refs #1

1 files changed, 2 insertions, 0 deletions

diff --git a/index.js b/index.js
index 1a5a5d5..51d81bd 100644
--- a/index.js
+++ b/index.js
@@ -166,6 +166,8 @@ var makeTimezoneBoundary = function(tzid, callback) {
       geom = intersection(geom, taskData)
     } else if(task.op === 'difference') {
       geom = diff(geom, taskData)
+    } else if(task.op === 'union') {
+      geom = union(geom, taskData)
     }
     cb()
   }, function(err) {