input: Write a function to find the key with the highest value in a dictionary.
  assert find_highest_value_key({"apple": 0, "orange": 25, "banana": 52})=="banana"
  assert find_highest_value_key({"a": 10, "b": 20, "c": 30})=="c"
  assert find_highest_value_key({"x": 1, "y": 2, "z": 3})=="z"
output: def find_highest_value_key(d):
      return max(d, key=d.get)