code: protected DoubleEditor getDoubleEditor(String key) {
          TypeEditor typeEditor = TYPE_EDITOR_MAP.get(key);
          if (typeEditor == null) {
              typeEditor = new DoubleEditor(this, sharedPreferences, key);
              TYPE_EDITOR_MAP.put(key, typeEditor);
          } else if (!(typeEditor instanceof DoubleEditor)) {
              throw new IllegalArgumentException(String.format("key %s is already used for other type", key));
          }
          return (DoubleEditor) typeEditor;
  
      }
docs: Call to get a {@link com.tale.prettysharedpreferences.DoubleEditor} object for the specific
  key. <code>NOTE:</code> There is a unique {@link com.tale.prettysharedpreferences.TypeEditor}
  object for a unique key.
  @param key The name of the preference.
  @return {@link com.tale.prettysharedpreferences.DoubleEditor} object to be store or retrieve
  a {@link java.lang.Double} value.