title: Create entry in helm template only if an entry exists in a map
body: <p>Assuming this map exists in my <code>values.yaml</code></p>
  <pre><code>something:
     somethingElse:
         variable1: value1
         variable2: value2
         variable3: value3
  </code></pre>
  <p>I want to create a helm template for a <code>kubernetes</code> <code>Secret</code> resource (although this is not of primary importance) if and only if say the key - value pair <code>variable2: value2</code> exists. (I am only actually interest to match the <code>variable2</code>'s existence, not what is the value of <code>value2</code>)</p>
  <p>I know how to <code>range</code> to include all entries</p>
  <pre><code>{{- range $name, $value := .Values.something.somethingElse }}
  {{indent 4 $name }}: {{ $value }}
  {{- end }}
  </code></pre>
  <p>but in pseudocode, what I want is</p>
  <pre><code>if variable2 in .Values.something.somethingElse
  
  variable2: value2
  </code></pre>
  <p>Is this somehow feasible using the <code>helm</code> templating language?</p>