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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 ssh_known_hosts_lines(application_name, user=None):
 """Return contents of known_hosts file for given application. :param application_name: Name of application eg nova-compute-something :type application_name: str :param user: The user that the ssh asserts are for. :type user: str """

    known_hosts_list = []
    with open(known_hosts(application_name, user)) as hosts:
        for hosts_line in hosts:
            if hosts_line.rstrip():
                known_hosts_list.append(hosts_line.rstrip())
    return(known_hosts_list)