input: Write a function named char_occurrences that takes an input string as its parameter and returns a dictionary where each key is a character from the string and the value is the number of times that character appears in the string.
  
  assert char_occurrences("Hello, World!") == {'H': 1, 'e': 1, 'l': 3, 'o': 2, ', ': 1, 'W': 1, 'r': 1, 'd': 1, '!': 1}
  assert char_occurrences("abracadabra") == {'a': 5, 'b': 2, 'r': 2, 'c': 1, 'd': 1}
  assert char_occurrences("") == {}
  assert char_occurrences("a" * 10) == {'a': 10}
output: def char_occurrences(input_string):
      result = {}
      for char in input_string:
          if char in result:
              result[char] += 1
          else:
              result[char] = 1
      return result