docs: def add_result(self, source, found, runtime):
          """
          Adds a new record to the statistics 'database'. This function is
          intended to be called after a website has been scraped. The arguments
          indicate the function that was called, the time taken to scrap the
          website and a boolean indicating if the lyrics were found or not.
          """
          self.source_stats[source.__name__].add_runtime(runtime)
          if found:
              self.source_stats[source.__name__].successes += 1
          else:
              self.source_stats[source.__name__].fails += 1