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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 agent_auth(transport, username):
 """ Attempt to authenticate to the given transport using any of the private keys available from an SSH agent. """

    
    agent = ssh.Agent()
    agent_keys = agent.get_keys()
    if len(agent_keys) == 0:
        return
        
    for key in agent_keys:
        print 'Trying ssh-agent key %s' % hexlify(key.get_fingerprint()),
        try:
            transport.auth_publickey(username, key)
            print '... success!'
            return
        except ssh.SSHException:
            print '... nope.'