input: Write a function to count the occurrence of each character in a given input string. Return a dictionary where the keys are the characters and the values are the counts of those characters.
  assert char_occurrences("Hello, World!")=={'H': 1, 'e': 1, 'l': 3, 'o': 2, ',': 1, ' ': 1, 'W': 1, 'r': 1, 'd': 1, '!': 1}
  assert char_occurrences("Python")=={'P': 1, 'y': 1, 't': 1, 'h': 1, 'o': 1, 'n': 1}
  assert char_occurrences("aabbcc")=={'a': 2, 'b': 2, 'c': 2}
  assert char_occurrences("")=={}
  assert char_occurrences("12345")=={'1': 1, '2': 1, '3': 1, '4': 1, '5': 1}
output: def char_occurrences(input_string):
      char_count = {}
      for char in input_string:
          if char in char_count:
              char_count[char] += 1
          else:
              char_count[char] = 1
      return char_count