Be consistent about the use of from-imports in random module (GH-11837)

Minor code clean-up.

Lib/random.py

@@ -43,8 +43,8 @@ from math import sqrt as _sqrt, acos as _acos, cos as _cos, sin as _sin
 from os import urandom as _urandom
 from _collections_abc import Set as _Set, Sequence as _Sequence
 from hashlib import sha512 as _sha512
-import itertools as _itertools
-import bisect as _bisect
+from itertools import accumulate as _accumulate
+from bisect import bisect as _bisect
 import os as _os
 
 __all__ = ["Random","seed","random","uniform","randint","choice","sample",
@@ -390,12 +390,12 @@ class Random(_random.Random):
                 _int = int
                 n += 0.0    # convert to float for a small speed improvement
                 return [population[_int(random() * n)] for i in range(k)]
-            cum_weights = list(_itertools.accumulate(weights))
+            cum_weights = list(_accumulate(weights))
         elif weights is not None:
             raise TypeError('Cannot specify both weights and cumulative weights')
         if len(cum_weights) != n:
             raise ValueError('The number of weights does not match the population')
-        bisect = _bisect.bisect
+        bisect = _bisect
         total = cum_weights[-1] + 0.0   # convert to float
         hi = n - 1
         return [population[bisect(cum_weights, random() * total, 0, hi)]