old_contents: import abc
  from collections import namedtuple
  
  
  Key = namedtuple('Key', ['x', 'y'])
  
  
  class Keyboard(metaclass=abc.ABCMeta):
      def __init__(self):
          pass
  
      @abc.abstractproperty
      def keys(self):
          pass
  
new_contents: import abc
  from collections import namedtuple
  
  
  Key = namedtuple('Key', ['x', 'y'])
  
  
  class Keyboard(metaclass=abc.ABCMeta):
      def __init__(self):
          pass
  
      @abc.abstractproperty
      def keys(self):
          pass
  
  
  class Actor(metaclass=abc.ABCMeta):
      def __init__(self):
          pass
  
      @abc.abstractmethod
      def evaluate(self, keyboard, layout, corpus):
          pass
  
subject: Implement Actor class