code: function deepMergeAssignments(objectName: string, properties: Object): string {
    const assignments = [];
    collectAssignmentsInto(assignments, [], properties);
    const jsAssignments = assignments.map(({path, value}) =>
      formatJSAssignment(objectName, path, value),
    );
    return jsAssignments.length === 0 ? '' : jsAssignments.join('\n');
  }
docs: Given a object of nested properties, return JavaScript text that would merge
  in an object named `objectName` by a series of individual assignments.