input: Write a function to find the maximum value in a nested dictionary.
  assert findMaxValue({'a': 1, 'b': {'c': 2, 'd': {'e': 3}}}) == 3
  assert findMaxValue({'a': 10, 'b': {'c': 20, 'd': {'e': 30, 'f': 25}}}) == 30
  assert findMaxValue({'a': 5, 'b': {'c': -2, 'd': {'e': 0, 'f': -1}}}) == 5
output: def findMaxValue(d):
      def max_in_dict(d):
          max_val = float('-inf')
          for key, value in d.items():
              if isinstance(value, dict):
                  max_val = max(max_val, max_in_dict(value))
              else:
                  max_val = max(max_val, value)
          return max_val
      return max_in_dict(d)