input: from typing import List
  
  def replace_all_occurrences(str: str, char: str, replacement: str) -> str:
      """Replace all occurrences of a specified character in a given string with the provided replacement character.
      >>> replace_all_occurrences("Hello World!", 'l', 'X')
      'HeXXo WorXd!'
      >>> replace_all_occurrences("Success", 's', 't')
      'Succett'
      """
      return str.replace(char, replacement)
    
  print(replace_all_occurrences("Hello World!", 'l', 'X'))
output:     return str.replace(char, replacement)