Redirect IP request to the name irule

I fixed problem like below and derived advantage from your reccomandations:

when HTTP_REQUEST {

      if { [string tolower [HTTP::host]] equals "webserver.test.local" } {

         if { [HTTP::uri] equals "/" } {

            HTTP::respond 301 Location "https://[HTTP::host]/yyy"

return

          }

      elseif { not ([HTTP::uri] starts_with "/yyy") } {

      HTTP::redirect "https://[HTTP::host]/yyy"

           node "10.20.1.15:4443"

}

 elseif { ([HTTP::host] starts_with "10.10.10.15") and not ([HTTP::uri] starts_with "/yyy") } {

      HTTP::redirect "https://webserver.test.local/yyy"

           }

}

But what is the logic behind the return keyword?