Subject Check output parameters' value on input
Author Dimitry Sibiryakov
Hello, All.

Do anybody know the reason why output parameters (such as transaction handle in
isc_start_transaction) are required to be NULL on input?
If you forget to clean the variable before calling isc_start_transaction(), you'll get
error "invalid transaction handle (expecting explicit transaction start)" which is rather
confusing because this function is exactly expected to do "explicit transaction start".