def upgrade_summary(data = None):
    """Returns a summary of a possible upgrade"""

    print "Generating summary"
    lp_Out = subprocess.PIPE
    slapt_call = subprocess.Popen('/usr/sbin/slapt-get --upgrade -s',
            bufsize=0, executable=None, stdin=None, \
            stdout=lp_Out, stderr=None, preexec_fn=None, \
            close_fds=False, shell=True, cwd=None, \
            env=None, universal_newlines=False, \
            startupinfo=None, creationflags=0)

    print "Waiting for slapt-get --upgrade -s"
    while slapt_call.poll() == None:
        if data:
            do_pulse_bar(data)
        yield True
    print "Done\nReading output"
    for package in slapt_call.stdout.readlines():
        if data:
            do_pulse_bar(data)
        #here you should process i and yield exactly what you
        #need. I will yield every line complete
        yield package
    print "Done"