anchor.diff:  <%-
  -  @nav_sections = []
  -  @subnav_sections = []
  +  @nav_sections ||= []
  +  @subnav_sections ||= []
     
     if is_logged_in_user?
       if user_has_permission?(:manage_cms)
  
positive.code:     @nav_sections += ImagineCmsAdditionalNavSections.is_a?(Proc) ? ImagineCmsAdditionalNavSections.call(self) : ImagineCmsAdditionalNavSections
    end
    
    #
    # how to use a Proc to add nav sections:
    #
    # ImagineCmsAdditionalNavSections = Proc.new { |context|
    #   nav_sections = []
    #
    #   context.instance_eval {
    #     if is_logged_in_user?
  
negative.code:   #     end
    #   }
    #
    #   addl_sections
    # }
  -%>
  <!DOCTYPE html>
  