new_contents: import random
  class RandomizedSet:
  
      def __init__(self):
          """
          Initialize your data structure here.
          """
          self.set = set()
          
  
      def insert(self, val):
          """
          Inserts a value to the set. Returns true if the set did not already contain the specified element.
          :type val: int
          :rtype: bool
          """
          if val not in self.set:
              self.set.add(val)
              return True
          return False
          
  
      def remove(self, val):
          """
          Removes a value from the set. Returns true if the set contained the specified element.
          :type val: int
          :rtype: bool
          """
          if val in self.set:
              self.set.remove(val)
              return True
          return False
          
  
      def getRandom(self):
          """
          Get a random element from the set.
          :rtype: int
          """
          length = len(self.set)
          index = random.randrange(length)
          return list(self.set)[index]
          
  
  
  # Your RandomizedSet object will be instantiated and called as such:
  # obj = RandomizedSet()
  # param_1 = obj.insert(val)
  # param_2 = obj.remove(val)
  # param_3 = obj.getRandom()
  
subject: Insert Delete GetRandom O(1)