\\class Solution(object):
def twoSum(self, nums, target):
buffer_dictionary = {}
for i in range(len(nums)):
if nums[i] in buffer_dictionary:
return [buffer_dictionary[nums[i]], i] #if a number shows up in the dictionary already that means the
#necesarry pair has been iterated on previously
else: # else is entirely optional
buffer_dictionary[target - nums[i]] = i
# we insert the required number to pair with should it exist later in the list of numbers