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/Doc/library/decimal.rst b/Doc/library/decimal.rst
index 1d987b8..3fa006b 100644
--- a/Doc/library/decimal.rst
+++ b/Doc/library/decimal.rst
@@ -1577,7 +1577,7 @@
            InvalidOperation
            Rounded
            Subnormal
-           FloatOperation
+           FloatOperation(DecimalException, exceptions.TypeError)
 
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