Need help with an array problem.

[SpreadTooThin]

Basically I think the problem is in converting from a 32 bit integer to
a 16 bit integer.

I have two arrays:
import array

a = array.array('L', [65537])
b = array.array('H', [0])

b[0] = a[0]

Which gives an overflow message....
So can't I truncate the long by discaring the upper bits ..
Like  b[0] = 0x0000FFFF & a[0]

How does one normally cast an object from long to short?