Transferring files between apps?

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Hello! Alright so I have a quick question. I have some files in a downloading app on my iphone 5 that I would like to move around. For example, some songs that I would like to put into my music app. Like I said, I have an iphone 5 (not jailbroken) and I don't currently have access to a computer. I've been searching for a file manager app but I can't seem to find one that will help me out. Any suggestions? Thanks!!

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