code: function exportResolverMap(backing: SchemaBacking) {
    backing.validate();
    return reduce(
      backing.types,
      (rmap, config, name) => {
        const fields = reduce(
          config.fields,
          (fmap, field, fieldName) => {
            if (_.isFunction(field.resolve)) {
              fmap[fieldName] = field.resolve;
            }
            return fmap;
          },
          {},
          true,
        );
        return _.keys(fields).length ? _.merge(rmap, { [name]: fields }) : rmap;
      },
      {},
      true,
    );
  }
docs: Exports a schema backing as a resolverMap consumable by
  graphql-tools and possibly other tools
  @param {*} backing