if value x == any value in list y: python

Question

I'm relatively new to python and want to do something like:

if value x == any value in list y:
   write x

this would operate wihtin a function, so only solutions which match a certain criteria would write to csv as they are generated

Answer 1

>>> x = 8
>>> if x in (1, 2, 3, 5, 8, 13, 21, 34, 55):
        print('x is an early Fibonacci number')
x is an early Fibonacci number

Answer 2

You may use the in syntax:

if x in ["a", "b", "c"]
   ... do stuff

And also if you care about the number of occurances of x you may use count:

if y.count(x) == 1
  ... do stuff