migrate from 4.X to 9.X iRules

Anybody can refer me to a document (if exists) what is best way to migrate iRules from 4.5 to 9.X? Are there any recommendations?

 

 

Here is example of one of the rules:

 

 

if (http_header("SSLClientCipher") matches_regex "bits=128" or "bits=256") {

 

if (exists http_header("SSLClientCertStatus")) {

 

if (http_header("SSLClientCertStatus") contains "OK") {

 

use pool eids.mymerchantoffice.com

 

}

 

else {

 

redirect to "https://%h/main/MyPortfolio/Eids.aspx?certinstalled=6"

 

}

 

}

 

else {

 

redirect to "https://%h/main/MyPortfolio/Eids.aspx?certinstalled=3"

 

}

 

}

 

else {

 

use pool client_info

 

}