当输入或输出信息中有包含字段的数组时，可以对数组中的每个元素执行某些转换，或者将几个输入数组合并到一个输出中。

When there is an array of fields in the input or output message, certain transforms are available to perform an action on each element of an array, or to merge several input arrays into one output.

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将数组中的所有元素合并起来成为一条字符串。每个元素可以指定他们的分隔标记。

Puts all the elements of an array into a string. The elements are separated by a specified delimiter.

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