input: Write a function to replace all occurrences of a character in a given string with the provided replacement character. 
  
  def replace_all_occurrences(str, char, replacement):
    return str.replace(char, replacement)
  
  assert replace_all_occurrences("Hello World!", 'l', 'X') == "HeXXo WorXd!"
  assert replace_all_occurrences("Python Programming", 'P', 'Q') == "Qython Qrogramming"
  assert replace_all_occurrences("", 'a', '*') == ""
  assert replace_all_occurrences("abcabc", 'c', 'z') == "abzabz"
  assert replace_all_occurrences("test", 't', 'T') == "TesT"
output: def replace_all_occurrences(str, char, replacement):
    return str.replace(char, replacement)