input: Write a function to count the occurrence of each character in the given input string. The function should return a dictionary where the keys are characters and the values are the counts of those characters in the string. If the input string is empty, the function should return an empty dictionary.
  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("aabbbcccc")=={'a': 2, 'b': 3, 'c': 4}
  assert char_occurrences("")=={}
  assert char_occurrences("AaBbCc")=={'A': 1, 'a': 1, 'B': 1, 'b': 1, 'C': 1, 'c': 1}
output: def char_occurrences(s):
      if not s:
          return {}
      char_count = {}
      for char in s:
          if char in char_count:
              char_count[char] += 1
          else:
              char_count[char] = 1
      return char_count