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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def combine_keys(pks: Iterable[Ed25519PublicPoint]) -> Ed25519PublicPoint: """Combine a list of Ed25519 points into a "global" CoSi key."""

    P = [_ed25519.decodepoint(pk) for pk in pks]
    combine = reduce(_ed25519.edwards_add, P)
    return Ed25519PublicPoint(_ed25519.encodepoint(combine))