code: func (r *REPL) loadInput(ctx context.Context, compiler *ast.Compiler) (ast.Value, error) {
  
  	q := topdown.NewQuery(ast.MustParseBody("data.repl.input = x")).
  		WithCompiler(compiler).
  		WithStore(r.store).
  		WithTransaction(r.txn)
  
  	qrs, err := q.Run(ctx)
  	if err != nil {
  		return nil, err
  	}
  
  	if len(qrs) != 1 {
  		return nil, nil
  	}
  
  	return qrs[0][ast.Var("x")].Value, nil
  }
docs: // loadInput returns the input defined in the REPL. The REPL loads the
  // input from the data.repl.input document.