code: def sign(self, storepass=None, keypass=None, keystore=None, apk=None, alias=None, name='app'):
      
      self.src_folder = self.get_src_folder()
      if keystore is None:
        (keystore, storepass, keypass, alias) = android_helper.get_default_keystore()
      dist = '%s/%s.apk' % ('/'.join(apk.split('/')[:-1]), name)
      android_helper.jarsign(storepass, keypass, keystore, apk, alias, path=self.path)
      android_helper.zipalign(apk, dist, build_tool=self.get_build_tool_version(), path=self.path)
docs: Signs (jarsign and zipalign) a target apk file based on keystore information, uses default debug keystore file by default.
  
      :param storepass(str): keystore file storepass
      :param keypass(str): keystore file keypass
      :param keystore(str): keystore file path
      :param apk(str): apk file path to be signed
      :param alias(str): keystore file alias
      :param name(str): signed apk name to be used by zipalign