code: function() {
        // If the instance is being queried before the data's been fetched
        // then return undefined.
        if(this.model_names.length === 0) {
          return undefined;
        }
        if(this.simpleSheet) {
          if(this.model_names.length > 1 && this.debug) {
            this.log("WARNING You have more than one sheet but are using simple sheet mode! Don't blame me when something goes wrong.");
          }
          return this.models[ this.model_names[0] ].all();
        } else {
          return this.models;
        }
      }
docs: /*
  What gets send to the callback
  if simpleSheet === true, then don't return an array of Tabletop.this.models,
  only return the first one's elements