old_contents: import datetime
  
  class Cache:
      EXPIRE_IN = 'expire_in'
  
      def __init__(self):
          self.store = {}
  
      def get(self, key):
          """Gets a value based upon a key.""" 
          self._check_expiry(key)        
          return self.store[key]['value']
  
      def set(self, dictionary, expire_in):
          """Sets a dictionary to the cache with a timedelta expiration."""
          for key in dictionary.keys():
              self.store[key] = {
                  Cache.EXPIRE_IN: datetime.datetime.now() + expire_in,
                  'value': dictionary[key]
              }
  
      def has(self, key):
          """Returns whether a key is in the cache."""
          self._check_expiry(key)
          return key in self.store
      
      def _check_expiry(self, key):
          """Removes a key/value pair if it's expired."""
          if key in self.store and datetime.datetime.now() > self.store[key][Cache.EXPIRE_IN]:
              self.store.pop(key, None)
          
  
new_contents: import datetime
  
  class Cache:
      EXPIRE_IN = 'expire_in'
      VALUE = 'value'
  
      def __init__(self):
          self.lock = False
          self.store = {}
  
      def get(self, key):
          """Gets a value based upon a key.""" 
          self._check_expiry(key)        
          return self.store[key][Cache.VALUE]
  
      def set(self, expire_in, *args):
          """Sets a dictionary to the cache with a timedelta expiration."""
          for arg in args:
              if isinstance(arg, dict):
                  for k,v in arg.items():
                      self._set(k, v, expire_in)
              else: 
                  for v in arg:
                      self._set(v[0], v[1], expire_in)
  
      def has(self, key):
          """Returns whether a key is in the cache."""
          self._check_expiry(key)
          return key in self.store
  
      def _set(self, key, value, expire_in):
          self.store[key] = {
              Cache.EXPIRE_IN: datetime.datetime.now() + expire_in,
              Cache.VALUE: value
          }
      
      def _check_expiry(self, key):
          """Removes a key/value pair if it's expired."""
          if not self.lock and key in self.store and datetime.datetime.now() > self.store[key][Cache.EXPIRE_IN]:
              self.store.pop(key, None)
          
  
subject: Change signature of set() method.