Write a function to find pair sum in a list.

1. Define function 'pairSum' which will accept two arguments, a integer list and a number.
2. List should have at least two elements in it.
3. Function should return pair of integers within list having sum equal to given number as argument.
4. Function should pass all test cases.

Instructions:

• Program should be written in file pair_sum.py

• Function name should be pairSum.

• Input

   Type:  List
   Value: ([1,2,3,4], 5)
  

• Expected Output

    Type:  List
    Value: [(1,4), (2,3)]