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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 get_nagios_unit_name(relation_name='nrpe-external-master'):
 """ Return the nagios unit name prepended with host_context if needed :param str relation_name: Name of relation nrpe sub joined to """

    host_context = get_nagios_hostcontext(relation_name)
    if host_context:
        unit = "%s:%s" % (host_context, local_unit())
    else:
        unit = local_unit()
    return unit