input: 
  def replace_all_occurrences(str: str, char: str, replacement: str) -> str:
      """ Replace all occurrences of a given character in a string with the provided replacement character.
      >>> replace_all_occurrences("Hello World!", 'l', 'X')
      'HeXXo WorXd!'
      >>> replace_all_occurrences("Python Programming", 'P', 'Z')
      'Zython Zrogramming'
      """
      return str.replace(char, replacement)
  
output:     return str.replace(char, replacement)