code: function addContext(newContext) {
    if (newContext && newContext.length) {
      _previousContext = _context
      _addUniqueItems(_context, newContext)
    }
    return _context
  }
docs: Adds the new context to genie's current context.
  Genie's context will maintain uniqueness, so don't
  worry about overloading genie's context with
  duplicates.
  @param {string|Array.<string>} newContext The context to add
  @returns {Array} Genie's new context
  @public