input: Write a python function to create a binomial tree.
  assert BinomialTree(3).create() == [1, 2, 2, 3]
  assert BinomialTree(4).create() == [1, 2, 2, 3, 3]
  assert BinomialTree(5).create() == [1, 2, 2, 3, 3, 4]
output: def BinomialTree(n):
      class BinomialTreeInner:
          def __init__(self, n):
              self.n = n
          
          def create(self):
              result = [1]
              for i in range(2, self.n + 1):
                  result.extend([i] * (i - 1))
              return result
              
      return BinomialTreeInner(n)