code: function determineValue(keys, doc) {
    try {
      for (const key of keys) {
        doc = doc[key];
      }
  
      /**
        the keys array should transition through any nesting,
        so any object is assumed to be enumValues:
          { value: 'string', enumValues: ['strings'] }
       */
      return typeof doc === 'object' ? doc.value : doc;
    } catch (error) { return doc; }
  }
docs: Traverse the passed document, according to keys, appropriating the desired value
  @param [String]: keys -- an array of keys determining the path to value
  @param Object: doc -- the document that contains the value at keys path
  @return any: -- the value at the end of keys path in document