[Zope] class Missing.Missing help

[Samir Mishra]

Hello All,

I have a ZSQL method executing a simple 'select' statement against a MS SQL
Server. Some of the rows/columns have missing values. On looking at the
variable 'type', I get -
<extension class Missing.Missing at 013130E0>

How do I test if the return value is a NULL value? e.g., as in 
if variable is None:
    do something...

If I assign this value to a variable in a dictionary, I get -
{'variable':Missing.Value}

Help much appreciated. Thx.

Regards,
Samir