iRule to drop or allow base on cookie value and date

when HTTP_REQUEST {

 Get day of month:
 set day [clock format [clock seconds] -format {%d}]
 Check if it is even
if {[clock format [clock seconds] -format {%d}] % 2 == 0 and }{

 Check if the cookie value is not null: 
[HTTP::cookie my_cookie] ne "" 
 
 Get the last char of the cookie value:
[string range [HTTP::cookie my_cookie] end end]

 Assign the last character of the cookie value to a variable, last_char
[set last_char [string range [HTTP::cookie my_cookie] end end]]

 Check if $last_char is an integer
[string is integer ...

 Check if the last character is even using modulus %
 string is integer: http://www.tcl.tk/man/tcl8.4/TclCmd/string.htmM23
if {[HTTP::cookie my_cookie] ne "" and [string is integer [set last_char [string range [HTTP::cookie my_cookie] end end]]] and $last_char % 2 == 0 }{

 Allow the request. Exit this event in this iRule so we do not block the request
return
}
} elseif {[HTTP::cookie my_cookie] ne "" and [string is integer [set last_char [string range [HTTP::cookie my_cookie] end end]]] and $last_char % 2 == 1}{
 Allow the request. Exit this event in this iRule so we do not block the request
return
}
 Default action is to block the request
HTTP::respond 403 content "you're blocked because you had cookie [HTTP::cookie my_cookie] and it is [clock format [clock seconds] -format {%d}] of the month"
}