Use the same exception hierarchy as decimal.py. FloatOperation now also
inherits from TypeError. Cleanup in module initialization to make repeated
import failures robust.
diff --git a/Lib/decimal.py b/Lib/decimal.py
index b6f66ab..6bd655b 100644
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -391,7 +391,7 @@
In all cases, Inexact, Rounded, and Subnormal will also be raised.
"""
-class FloatOperation(DecimalException):
+class FloatOperation(DecimalException, TypeError):
"""Enable stricter semantics for mixing floats and Decimals.
If the signal is not trapped (default), mixing floats and Decimals is