Begin by creating a recursive concat function.

首先创建递归的concat函数。

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As an example to illustrate one of these functions, let's consider the array concat function.

作为演示其中一个这类函数的例子，让我们考虑array concat函数。

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As an example to illustrate one of these functions, consider the array concat function with respect to Table 3.

作为一个例子，考虑表3中的array concat函数。

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