fix class unit

Shlomi Kushchi · web-flow · commit 088c572c3d3c · 2020-05-05T21:54:58.000+03:00
diff --git a/alpaca_trade_api/entity.py b/alpaca_trade_api/entity.py
@@ -139,7 +139,7 @@ def __getattr__(self, key):
 
 
 class _NanoTimestamped(_Timestamped):
-    unit = 'ms'
+    unit = 'ns'
 
 
 class _MicroTimestamped(_Timestamped):
