old_contents: 
  from drest import exc, meta, interface
  
  def validate(obj):
      """Validates a handler implementation against the IResponse interface."""
      members = [
          'status',
          'data',
          ]
      metas = []
      interface.validate(IResponse, obj, members, metas)
      
  class IResponse(interface.Interface):
      """
      This class defines the Response Handler Interface.  Classes that 
      implement this handler must provide the methods and attributes defined 
      below.
      
      All implementations must provide sane 'default' functionality when 
      instantiated with no arguments.  Meaning, it can and should accept 
      optional parameters that alter how it functions, but can not require
      any parameters.  
      
      Implementations do *not* subclass from interfaces.
              
      """
      status = interface.Attribute('The response status (i.e. HTTP code).')
      data = interface.Attribute('The data returned by the request.')
      headers = interface.Attribute('The headers returned by the request.')
      
  class ResponseHandler(meta.MetaMixin):
      class Meta:
          pass
      
      status = None
      data = None
      headers = None
      
      def __init__(self, status, data, headers):
          self.status = int(status)
          self.data = data
          self.headers = headers
  
new_contents: 
  from drest import exc, meta, interface
  
  def validate(obj):
      """Validates a handler implementation against the IResponse interface."""
      members = [
          'status',
          'data',
          'headers',
          ]
      metas = []
      interface.validate(IResponse, obj, members, metas)
      
  class IResponse(interface.Interface):
      """
      This class defines the Response Handler Interface.  Classes that 
      implement this handler must provide the methods and attributes defined 
      below.
      
      All implementations must provide sane 'default' functionality when 
      instantiated with no arguments.  Meaning, it can and should accept 
      optional parameters that alter how it functions, but can not require
      any parameters.  
      
      Implementations do *not* subclass from interfaces.
              
      """
      status = interface.Attribute('The response status (i.e. HTTP code).')
      data = interface.Attribute('The data returned by the request.')
      headers = interface.Attribute('The headers returned by the request.')
      
  class ResponseHandler(meta.MetaMixin):
      class Meta:
          pass
      
      status = None
      data = None
      headers = None
      
      def __init__(self, status, data, headers):
          self.status = int(status)
          self.data = data
          self.headers = headers
  
subject: add headers to validator