title: How to apply a formatter in nested translations with i18next
body: <p>I would like to format nested translations with i18next</p>
  <p>Given the resources:</p>
  <pre class="lang-json prettyprint-override"><code>{
    translation: {
      en: {
        food: 'bread',
        food_is_good: &quot;$t(food), that's not bad&quot;,
      },
    },
  }
  </code></pre>
  <p>and a formatting function:</p>
  <pre class="lang-js prettyprint-override"><code>function format(value, format, lng) {
    if (value == undefined) return value;
    switch (format) {
      case 'capitalize':
        return _.capitalize(value);
      default:
        return value;
    }
  }
  </code></pre>
  <p>that is used in the initialization of i18next:</p>
  <pre class="lang-js prettyprint-override"><code>...
    interpolation: { format: format },
  ...
  </code></pre>
  <p>I would like the output to be &quot;Bread, that is not bad&quot;.
  So I hoped that something like:</p>
  <pre class="lang-json prettyprint-override"><code>{
    ...
    &quot;food_is_good_1&quot; : &quot;$t(food,capitalize), that's not bad&quot;,
    &quot;food_is_good_2&quot; : &quot;{{$t(food),capitalize}}, that's not bad&quot;,
    &quot;food_is_good_3&quot; : &quot;{{food,capitalize}}, that's not bad&quot;,
    ...
  }
  </code></pre>
  <p>would do the trick.
  The first option displays errors : <code>&quot;failed parsing options string in nesting&quot;</code>
  The last two options warn: <code>missed to pass in variable food,capitalize for interpolating {{food,capitalize}}</code></p>