code: def build_headers(self):
          '''
          Return the list of headers as two-tuples
          '''
          if not 'Content-Type' in self.headers:
              content_type = self.content_type
              if self.encoding != DEFAULT_ENCODING:
                  content_type += '; charset=%s' % self.encoding
              self.headers['Content-Type'] = content_type
  
          headers = list(self.headers.items())
          # Append cookies
          headers += [
              ('Set-Cookie', cookie.OutputString())
              for cookie in self.cookies.values()
          ]
          return headerf build_headers(self):
          '''
          Return the list of headers as two-tuples
          '''
          if not 'Content-Type' in self.headers:
              content_type = self.content_type
              if self.encoding != DEFAULT_ENCODING:
                  content_type += '; charset=%s' % self.encoding
              self.headers['Content-Type'] = content_type
  
          headers = list(self.headers.items())
          # Append cookies
          headers += [
              ('Set-Cookie', cookie.OutputString())
              for cookie in self.cookies.values()
          ]
          return headers
docs: Return the list of headers as two-tuples