## Handshakes That Dont Cross

You are given an even number of people num_people that stand around a circle and each person shakes hands with someone else, so that there are num_people / 2 handshakes total. Return the number of ways these handshakes could occur such that none of the handshakes cross. Since this number could be very big, return the answer mod 10^9 + 7 Example 1 Input: num_people = 2 Output: 1 Example 2 Input: num_people = 4 Output: 2 Explanation: There are two ways to do it, the first way is [(1,2),(3,4)] and the second one is [(2,3),(4,1)].