Function input parameter prefix set

[anp135]

function fn_prfx_chk(prefix set prfx_accept) {
    print "net: ", net, "; prefix set: ", prfx_accept, net !~ prfx_accept;
}
...
protocol bgp .... {
    ...
    input filter { fn_prfx_chk([ 198.51.100.0/24, 203.0.113.0/24+ ]); };
    ...
}

In the log file we see:

<INFO> net: 98.51.100.0/24; prefix set: [98.51.100.0/120{::1ff}, 203.0.113.0/120{::1ff}]FALSE
<INFO> net: 203.0.113.0/24; prefix set: [98.51.100.0/120{::1ff}, 203.0.113.0/120{::1ff}]FALSE

We tried define prefix set and set to function input param prefix set variable, but the same: durind prefix set comes to func over input parameter, then all prefixes modified: /24 -> /120{::1ff}

How we can put pefix set as input parameters to functions?