getValue method
Retrieves a value from SharedPreferences with a namespaced key.
key is the original key.
defaultValue is the value to be returned if the key does not exist.
Returns the stored value or the defaultValue if the key does not exist.
Implementation
Future<dynamic> getValue(String key, {dynamic defaultValue}) async {
return await SharedPreferencesWrapper.getValue(_getKey(key),
defaultValue: defaultValue);
}