[work] Add start time argument

bin/work

@@ -132,13 +132,17 @@ def work(args):
 
 def work_start(args):
     fields = get_today_fields()
-    hour = start_time.strftime("%H:%M")
+    try:
+        hour = datetime.strptime(args.time, "%H:%M")
+    except ValueError:
+        die("Error: {} is not a valid time".format(args.time))
     if fields:
         die("You already started working")
     with open(TODAY_FILE, "a") as f:
         f.write("{},{}".format(
-            start_time.strftime("%Y-%m-%d"), hour))
-    log("Started working at {}".format(hour))
+            start_time.strftime("%Y-%m-%d"),
+            hour.strftime("%H:%M")))
+        log("Started working at {}".format(hour.strftime("%H:%M")))
 
 
 def work_pause(args):
@@ -249,9 +253,10 @@ if __name__ == "__main__":
     parse_parser = commands.add_parser("parse")
 
     start_parser.set_defaults(func=work_start)
+    start_parser.add_argument("time", nargs="?", default=datetime.now().strftime("%H:%M"))
     pause_parser.set_defaults(func=work_pause)
-    end_parser.add_argument("description")
     end_parser.set_defaults(func=work_end)
+    end_parser.add_argument("description")
     export_parser.set_defaults(func=work_export)
     parse_parser.set_defaults(func=work_parse)
     parse_parser.add_argument("file")