code: def do(self, func, *args, **kwargs):
          
          if not callable(func):
              func = getattr(self.engine.function, func)
          func(self, *args, **kwargs)
          return self
docs: Apply the function to myself, and return myself.
  
          Look up the function in the database if needed. Pass it any
          arguments given, keyword or positional.
  
          Useful chiefly when chaining.