input: Write a python function to add two frequency lists using numpy and return the result as a list.
  assert add_frequencies([1, 2, 3], [4, 5, 6]) == [5, 7, 9]
  assert add_frequencies([10, 20, 30], [1, 2, 3]) == [11, 22, 33]
  assert add_frequencies([0, 0, 0], [0, 0, 0]) == [0, 0, 0]
output: import numpy as np
  
  def add_frequencies(list1, list2):
      return (np.array(list1) + np.array(list2)).tolist()