Help need to create a irule for limit Client Connection

 From http://devcentral.f5.com/wiki/iRules.table.ashx
 Limit each client IP address to 20 concurrent connections
when CLIENT_ACCEPTED {

    Max connections per client IP
   set limit 20

    Set a subtable name with a standard prefix and the client IP
   set tbl "connlimit:[IP::client_addr]"

    Use a key of the client IP:port
   set key "[IP::client_addr][TCP::client_port]"

    Check if the subtable has over X entries
   if { [table keys -subtable $tbl -count] >= $limit } {
      log local0. "[IP::client_addr]:[TCP::client_port]: Rejecting connection ([table keys -subtable $tbl -count] connections / limit: $limit)"
      reject
   } else {

       Add the client IP:port to the client IP-specific subtable 
         with a max lifetime of 1800 seconds (30min)
      table set -subtable $tbl $key "ignored" 1800

      log local0. "[IP::client_addr]:[TCP::client_port]: Allowing connection ([table keys -subtable $tbl -count] connections / limit: $limit)"
   }
}

when CLIENT_CLOSED {
    When the client connection is closed, remove the table entry
   table delete -subtable $tbl $key
   log local0. "[IP::client_addr]:[TCP::client_port]: Decrementing ([table keys -subtable $tbl -count] connections / limit: $limit)"
}