org-element: headline's :title is sometimes string, sometimes list

[Hraban Luyat <hraban@0brg.net>]

Hi all.

I'll let the code speak:

     (with-temp-buffer
       (org-mode)
       (insert "* Hello")
       (cl-flet ((say-type (prefix hl)
                   (message "Headline title from %s is of type: %s"
                            prefix
                            (type-of (org-element-property :title hl)))))
         (org-element-map (org-element-parse-buffer) 'headline
           (lambda (hl) (say-type "map" hl)))
         (goto-char (point-min))
         (say-type "context" (org-element-context))
         (say-type "at-point" (org-element-at-point))))

I expect: "string" everywhere.

I get:

     Headline title from map is of type: cons
     Headline title from context is of type: string
     Headline title from at-point is of type: string

Question 1: Do you know what that `cons' structure is? Where is it 
documented, how would I go about figuring this out myself? The 
org-element API documentation is daunting.

Question 2: how do I reliably get the title as a string? Properties are 
fine, I don't mind, but that weird list structure is awkward to handle.

Thank you

Hraban