Check element exists in array

Question

In PHP there a function called isset() to check if something (like an array index) exists and has a value. How about Python?

I need to use this on arrays because I get \

Answer 1

has_key is fast and efficient.

Instead of array use an hash:

valueTo1={"a","b","c"}

if valueTo1.has_key("a"):
        print "Found key in dictionary"