input: Write a function to implement a MinHeap data structure with insert and fix_new_item methods.
  assert h.heap_list == [0, 5, 7, 6, 10]
  assert h.current_size == 4
output: class MinHeap:
      def __init__(self):
          self.heap_list = [0]
          self.current_size = 0
  
      def insert(self, k):
          self.heap_list.append(k)
          self.current_size += 1
          self.fix_new_item(self.current_size)
  
      def fix_new_item(self, i):
          while i // 2 > 0:
              if self.heap_list[i] < self.heap_list[i // 2]:
                  self.heap_list[i], self.heap_list[i // 2] = self.heap_list[i // 2], self.heap_list[i]
              i = i // 2
  
  # Example usage and assertions
  h = MinHeap()
  h.insert(10)
  h.insert(5)
  h.insert(6)
  h.insert(7)
  
  assert h.heap_list == [0, 5, 7, 6, 10]
  assert h.current_size == 4