I defined an array items. The values ​​in the array were dynamically added by calling the interface through a for loop. I added an index and the childrenItems array. At the same time, I called the interface of the list in the for loop, which is childrenItems. content, so I need to nest a for loop to push the content of childrenItems, but I don’t know why my printing result is like this. Please explain it, thank you

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