Method traverse

packages/graph/src/Steps.ts:4726–4763

(
    _source: GraphSource<any>,
    input: Iterable<TraversalPath<any, any, any>>,
    context?: QueryContext,
  )

  }

  public *traverse(
    _source: GraphSource<any>,
    input: Iterable<TraversalPath<any, any, any>>,
    context?: QueryContext,
  ): IterableIterator<unknown> {
    const { items } = this.config;

    // Check if this is a single item and what type it is
    const singleItem = items.length === 1 ? items[0] : null;
    const isPlainVariableRef =
      singleItem &&
      typeof singleItem.expression === "object" &&
      singleItem.expression !== null &&
      "type" in singleItem.expression &&
      singleItem.expression.type === "variableRef";

    for (const path of input) {
      this.traversed++;

      const results: unknown[] = [];
      for (const item of items) {
        const value = resolveConditionValue(path, item.expression, context);
        results.push(value);
      }

      this.emitted++;

      // For backward compatibility with SelectStep + ValuesStep behavior:
      // - Plain variable refs (RETURN a) yield array: [value]
      // - Property access/functions (RETURN a.name, RETURN id(a)) yield value directly
      // - Multiple items always yield array
      if (items.length === 1 && !isPlainVariableRef) {
        yield results[0];
      } else {
        yield results;
      }
    }
  }

  public override clone(partial?: Partial<ExpressionReturnStepConfig>): ExpressionReturnStep {
    return new ExpressionReturnStep({