Updated per code review comments

Author: cognitivegears

adafruit_datetime.py

@@ -1284,8 +1284,7 @@ def _fromtimestamp(cls, t, utc, tz):
         A timezone info object may be passed in as well.
         """
         if isinstance(t, float):
-            frac = t - int(t)
-            t = int(t)
+            frac, t = _math.modf(t)
             us = round(frac * 1e6)
             if us >= 1000000:
                 t += 1
@@ -1294,7 +1293,6 @@ def _fromtimestamp(cls, t, utc, tz):
                 t -= 1
                 us += 1000000
         else:
-            frac = 0
             us = 0
 
         if utc: