docs: def get_default_keystore(prefix='AG_'):
    """
    Gets the default keystore information based on environment variables and a prefix.
  
    $PREFIX_KEYSTORE_PATH - keystore file path, default is opt/digger/debug.keystore
    $PREFIX_KEYSTORE_STOREPASS - keystore storepass, default is android
    $PREFIX_KEYSTORE_KEYPASS - keystore keypass, default is android
    $PREFIX_KEYSTORE_ALIAS - keystore alias, default is androiddebug
    
    :param prefix(str) - A prefix to be used for environment variables, default is AG_.
  
    Returns:
      A tuple containing the keystore information: (path, storepass, keypass, alias)
    """
    path = os.environ.get('%s_KEYSTORE_PATH' % prefix, config.keystore.path)
    storepass = os.environ.get('%s_KEYSTORE_STOREPASS' % prefix, config.keystore.storepass)
    keypass = os.environ.get('%s_KEYSTORE_KEYPASS' % prefix, config.keystore.keypass)
    alias = os.environ.get('%s_KEYSTORE_ALIAS' % prefix, config.keystore.alias)
    return (path, storepass, keypass, alias)