update windows build to Python 3.7

Lib/lib2to3/fixes/fix_paren.py

@@ -0,0 +1,44 @@
+"""Fixer that addes parentheses where they are required
+
+This converts ``[x for x in 1, 2]`` to ``[x for x in (1, 2)]``."""
+
+# By Taek Joo Kim and Benjamin Peterson
+
+# Local imports
+from .. import fixer_base
+from ..fixer_util import LParen, RParen
+
+# XXX This doesn't support nested for loops like [x for x in 1, 2 for x in 1, 2]
+class FixParen(fixer_base.BaseFix):
+    BM_compatible = True
+
+    PATTERN = """
+        atom< ('[' | '(')
+            (listmaker< any
+                comp_for<
+                    'for' NAME 'in'
+                    target=testlist_safe< any (',' any)+ [',']
+                     >
+                    [any]
+                >
+            >
+            |
+            testlist_gexp< any
+                comp_for<
+                    'for' NAME 'in'
+                    target=testlist_safe< any (',' any)+ [',']
+                     >
+                    [any]
+                >
+            >)
+        (']' | ')') >
+    """
+
+    def transform(self, node, results):
+        target = results["target"]
+
+        lparen = LParen()
+        lparen.prefix = target.prefix
+        target.prefix = "" # Make it hug the parentheses
+        target.insert_child(0, lparen)
+        target.append_child(RParen())