This is not a PHP function. It is likely that you have an included file or code somewhere which defines this.
Indeed because if you go into the official documentation and manually put the function into the url a 404 comes up and when searching the official documentation it does not appear. /manual/en/function.tabs.php
Try your code without including any files and I bet the function will not exist.
root = tkinter.Tk()
buttons=[i for i in range(10)]
#If specific button is pressed, output "YES"
for num in buttons: