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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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)