Question: How to get random characters in Maple?

Given a list of n characters, for example [a,1,!,#,@,B,...].
Please help me use Maple command to randomly pick k elements,
 each element consists of q consecutive random characters,
 for example, randomly pick 4 elements,
 each element consists of 3 consecutive random characters
 a1@, aa&, BC!, 90%. Thank you very much for your help!
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