code: function resolveEdge(edge: Edge): string {
    try {
      return resolve.sync(edge.end, {basedir: path.dirname(edge.start)});
    } catch (e) {
      process.stderr.write(`Error: resolving '${edge.end}' from '${edge.start}'\n`);
      return '';
    }
  }
docs: Returns the empty string if unable to resolve module.