code: function ensureContainerStateIdentifiers (container) {
    const domElement = container[$domElement]
    const template = getTemplateFromDomElement(domElement)
    const tokens = getTokens(template)
    const identifiers = getIdentifiersFromTokens(tokens)
    const update = {}
    const state = container.state
    if (identifiers) {
      for (let key in identifiers) {
        if (undefined === state[key])
          update[key] = identifiers[key]
      }
  
      container.define(update)
    }
    return identifiers || null
  }
docs: Ensures container state identifiers (tokens) derived from
  the DOM element source are defined on the state if not
  already. This is useful to prevent reference errors from
  being thrown when ES6 templates are evaulated in starplate's
  VM.
  
  @private
  @param {Container} container
  @return {Object} identifiers