no need to convert set to list before sorting

Author: Conengmo

folium/plugins/time_slider_choropleth.py

@@ -150,7 +150,6 @@ def __init__(self, data, styledict, name=None, overlay=True, control=True,
         timestamps = set()
         for feature in styledict.values():
             timestamps.update(set(feature.keys()))
-        timestamps = list(timestamps)
         try:
             timestamps = sorted(timestamps, key=int)
         except (TypeError, ValueError):