input: Write a python function to calculate the frequency of each character in a list of strings.
  assert character_frequency(['hello', 'world']) == [{'h': 1, 'e': 1, 'l': 2, 'o': 1}, {'w': 1, 'o': 1, 'r': 1, 'l': 1, 'd': 1}]
  assert character_frequency(['test', 'example']) == [{'t': 2, 'e': 1, 's': 1}, {'e': 2, 'x': 1, 'a': 1, 'm': 1, 'p': 1, 'l': 1}]
  assert character_frequency(['a', 'bb', 'ccc']) == [{'a': 1}, {'b': 2}, {'c': 3}]
output: def character_frequency(strings):
      result = []
      for s in strings:
          freq = {}
          for char in s:
              if char in freq:
                  freq[char] += 1
              else:
                  freq[char] = 1
          result.append(freq)
      return result