handling multiple attachments

The send email function shows an 'attachments' input, however I can find no details on how to populate this input.

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I see that the input is a List(Number) data type, and the function example shows it to be an array of numbers:

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As the attachment field in the workflow start form only accepts a single file then if there is a need for multiple attachments then I would need to add multiple attachment questions.

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However I can find no way to then collect the multiple attachment variables into the attachments variable.
Any ideas on how to send out all the attachments from the form through the send email function?