Python in Field Caluclator: why does this cause an error?

Discussion created by ground_hogg on Apr 13, 2011
Latest reply on Apr 14, 2011 by ground_hogg
here is the code:

import arcpy, os, math

temp1 = !FID!

seems pretty straight forward, yet throws an error.  I saw other examples where they quotes were removed, that does not work either.  I can get the textual functions like 'myfield'.capitilize to work, but I can't declare a variable and assign it a field value.