Update for new flake8 checks (#423)

Update python code for new flake8 type is checks

python-impl/ec.py

@@ -25,7 +25,7 @@ def __init__(self, x, y, infinity: bool, ec=default_ec):
         if (
             (not isinstance(x, Fq) and not isinstance(x, FieldExtBase))
             or (not isinstance(y, Fq) and not isinstance(y, FieldExtBase))
-            or type(x) != type(y)
+            or type(x) is not type(y)
         ):
             raise Exception("x,y should be field elements")
         self.FE = type(x)

python-impl/util.py

@@ -4,21 +4,21 @@
 
 
 def hash256(m):
-    if type(m) != bytes:
+    if type(m) is not bytes:
         m = m.encode("utf-8")
     return hashlib.sha256(m).digest()
 
 
 def hash512(m):
-    if type(m) != bytes:
+    if type(m) is not bytes:
         m = m.encode("utf-8")
     return hash256(m + bytes([0])) + hash256(m + bytes([1]))
 
 
 def hmac256(m, k):
-    if type(m) != bytes and type(m) != bytearray:
+    if type(m) is not bytes and type(m) is not bytearray:
         m = m.encode("utf-8")
-    if type(k) != bytes and type(k) != bytearray:
+    if type(k) is not bytes and type(k) is not bytearray:
         k = k.encode("utf-8")
     k = bytes(k)
     if len(k) > HMAC_BLOCK_SIZE: