code: function getState(element) {
    assertType(element, Node, false, 'Invalid element specified');
  
    let state = element.state || element.getAttribute(Directive.STATE);
  
    if (!state || state === '')
      return null;
    else
      return state;
  }
docs: Gets the current state of a DOM element as defined by Directive.STATE.
  
  @param {Node} element - Target element.
  
  @return {string} State of the target element.
  
  @alias module:requiem~dom.getState