Split Fountain Scenes

set stringToFind to "INT."
set stringToReplace to "===
INT."

set theFile to choose file
set theContent to read theFile as «class utf8»
set {oldTID, AppleScript's text item delimiters} to {AppleScript's text item delimiters, stringToFind}
set ti to every text item of theContent
set AppleScript's text item delimiters to stringToReplace
set newContent to ti as string
set AppleScript's text item delimiters to oldTID

set stringToFind to "EXT."
set stringToReplace to "===
EXT."
set {oldTID, AppleScript's text item delimiters} to {AppleScript's text item delimiters, stringToFind}
set ti to every text item of newContent
set AppleScript's text item delimiters to stringToReplace
set finalContent to ti as string

set AppleScript's text item delimiters to oldTID


try
    set fd to open for access theFile with write permission
    set eof of fd to 0
    write finalContent to fd as «class utf8»
    close access fd
on error
    close access theFile
end try