My most common python programming error is to spell a
variable different ways in different parts of a
program. Often this generates no warnings, and is a
difficult problem to track down.

The Zen of Python says that 'Explicit is better than
Implicit'. I would like it if I could set an option so
that I had to explicitly declare variables before I can
use them. eg.
x = 5
would generate a warning, but
x = int()
x = 5
would not.

I do believe that explicit is better than implicit with
respect to programming; and I know that this feature
would save me a _lot_ of debugging on my larger python
projects.