updating dictionaries from/to dictionaries

[John Machin]

On Aug 15, 11:23 am, Edwin.Mad... at VerizonWireless.com wrote:
> if the values for any of the keys are None, both do not work as can be seen below!!.
>

If any of the values are None, nothing can work. The OP justifiably
(given his problem domain (bigram frequencies)) expects that all
values will be integers. If this is not the case, it means that the
code that populates his dictionaries is majorly stuffed, an exception
will be raised, and he can fix it.