remove annotations import (#31)

Author: zhenglongjiepheonix

ppq/quantization/algorithm/training.py

@@ -1,6 +1,4 @@
 # TODO move training logic to here.
-from __future__ import annotations
-
 import random
 from math import sqrt
 from random import randint
@@ -650,7 +648,7 @@ def __init__(self,
         self._masters          = []
 
     @ property
-    def masters(self) -> List[StraightThroughEstimateDelegator]:
+    def masters(self):
         return self._masters
 
     @ masters.setter
@@ -675,6 +673,7 @@ def finalize(self) -> None:
                 # bias
                 scale = self.scale_multiplier
                 for delegator in self.masters:
+                    assert isinstance(delegator, StraightThroughEstimateDelegator)
                     scale = scale * delegator.scale.data.abs()
                 self.config.scale = scale