As far as I understand it, we need 4 call back functions:
from the book request need to extract the main characters - this can then return a list of the characters api url's to be used in the character request.
from the character requests need to extract and return the actor name, to be used in the first movieDB request.
From the first movieDB request need to extract and return the actor ID to be used in the second request.
From the second movieDB request need to extract and return a path to create a link to a website (either to iMDB or movieDB). Can extract other things as a stretch goal (issue #18 )
need functions to extract data from the various API requests