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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 _legacy_pubs(buf):
 """SSH v1 public keys are not supported."""

    leftover = buf.read()
    if leftover:
        log.warning('skipping leftover: %r', leftover)
    code = util.pack('B', msg_code('SSH_AGENT_RSA_IDENTITIES_ANSWER'))
    num = util.pack('L', 0)  # no SSH v1 keys
    return util.frame(code, num)