'This method returns a list of server sides to try to include.
:return: A string, see above.'

def _get_ssi_strings(self):

    (yield ('<!--#exec    cmd="echo    -n    %s;echo    -n    %s"    -->' % get_seeds()))
    (yield ('<!--#set    var="SEED_A"    value="%s"    --><!--#echo    var="SEED_A"    --><!--#set    var="SEED_B"    value="%s"    --><!--#echo    var="SEED_B"    -->' % get_seeds()))
    (yield ('{math    equation="x    *    y"    x=%s    y=%s}' % get_seeds()))
    (yield ('${%s    *    %s}' % get_seeds()))
    (yield ('{{%s    *    %s}}' % get_seeds()))
    (yield ('{%s    *    %s}' % get_seeds()))
