1 files changed, 19 insertions, 21 deletions

diff --git a/src/cryptography/utils.py b/src/cryptography/utils.py
index cbbae3a79..bdb3dbf47 100644
--- a/src/cryptography/utils.py
+++ b/src/cryptography/utils.py
@@ -20,22 +20,20 @@ class CryptographyDeprecationWarning(UserWarning):
 # Several APIs were deprecated with no specific end-of-life date because of the
 # ubiquity of their use. They should not be removed until we agree on when that
 # cycle ends.
-PersistentlyDeprecated = CryptographyDeprecationWarning
-DeprecatedIn21 = CryptographyDeprecationWarning
-DeprecatedIn23 = CryptographyDeprecationWarning
-DeprecatedIn25 = CryptographyDeprecationWarning
+PersistentlyDeprecated2017 = CryptographyDeprecationWarning
+PersistentlyDeprecated2019 = CryptographyDeprecationWarning
 
 
 def _check_bytes(name, value):
     if not isinstance(value, bytes):
-        raise TypeError("{0} must be bytes".format(name))
+        raise TypeError("{} must be bytes".format(name))
 
 
 def _check_byteslike(name, value):
     try:
         memoryview(value)
     except TypeError:
-        raise TypeError("{0} must be bytes-like".format(name))
+        raise TypeError("{} must be bytes-like".format(name))
 
 
 def read_only_property(name):
@@ -47,6 +45,7 @@ def register_interface(iface):
         verify_interface(iface, klass)
         iface.register(klass)
         return klass
+
     return register_decorator
 
 
@@ -56,27 +55,33 @@ def register_interface_if(predicate, iface):
             verify_interface(iface, klass)
             iface.register(klass)
         return klass
+
     return register_decorator
 
 
 if hasattr(int, "from_bytes"):
     int_from_bytes = int.from_bytes
 else:
+
     def int_from_bytes(data, byteorder, signed=False):
-        assert byteorder == 'big'
+        assert byteorder == "big"
         assert not signed
 
         return int(binascii.hexlify(data), 16)
 
 
 if hasattr(int, "to_bytes"):
+
     def int_to_bytes(integer, length=None):
         return integer.to_bytes(
-            length or (integer.bit_length() + 7) // 8 or 1, 'big'
+            length or (integer.bit_length() + 7) // 8 or 1, "big"
         )
+
+
 else:
+
     def int_to_bytes(integer, length=None):
-        hex_string = '%x' % integer
+        hex_string = "%x" % integer
         if length is None:
             n = len(hex_string)
         else:
@@ -98,7 +103,7 @@ def verify_interface(iface, klass):
     for method in iface.__abstractmethods__:
         if not hasattr(klass, method):
             raise InterfaceNotImplemented(
-                "{0} is missing a {1!r} method".format(klass, method)
+                "{} is missing a {!r} method".format(klass, method)
             )
         if isinstance(getattr(iface, method), abc.abstractproperty):
             # Can't properly verify these yet.
@@ -107,19 +112,11 @@ def verify_interface(iface, klass):
         actual = signature(getattr(klass, method))
         if sig != actual:
             raise InterfaceNotImplemented(
-                "{0}.{1}'s signature differs from the expected. Expected: "
-                "{2!r}. Received: {3!r}".format(
-                    klass, method, sig, actual
-                )
+                "{}.{}'s signature differs from the expected. Expected: "
+                "{!r}. Received: {!r}".format(klass, method, sig, actual)
             )
 
 
-# No longer needed as of 2.2, but retained because we have external consumers
-# who use it.
-def bit_length(x):
-    return x.bit_length()
-
-
 class _DeprecatedValue(object):
     def __init__(self, value, message, warning_class):
         self.value = value
@@ -160,7 +157,7 @@ def deprecated(value, module_name, message, warning_class):
 
 
 def cached_property(func):
-    cached_name = "_cached_{0}".format(func)
+    cached_name = "_cached_{}".format(func)
     sentinel = object()
 
     def inner(instance):
@@ -170,4 +167,5 @@ def cached_property(func):
         result = func(instance)
         setattr(instance, cached_name, result)
         return result
+
     return property(inner)