input: Write a function to replace all occurrences of a character in a 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', 'Z') == "Zython Zrogramming"  
  assert replace_all_occurrences("Coding is fun!", 'o', 'Q') == "Ciding is fun!"  
  assert replace_all_occurrences("", 'a', 'b') == ""  
  assert replace_all_occurrences("Hello", 'a', 'b') == "Hello"
output: def replace_all_occurrences(str, char, replacement):
    return str.replace(char, replacement)