code: def get_placeholder_formats_list(self, format_string):
          
          placeholders = []
          # Tokenize the format string and process them
          for token in self.tokens(format_string):
              if token.group("placeholder"):
                  placeholders.append((token.group("key"), token.group("format")))
          return placeholders
docs: Parses the format_string and returns a list of tuples
          (placeholder, format).