numeric func
A function to revisit the previous page in web_window’s history list.
A value of 0 is returned when successful. A value of 1 is returned on error.
The code of the function cannot be redefined.
window.go_back (<window>)
The function may be called in one of two ways:
# Assume mywin is the web window identifier window.go_back(mywin)or
mywin.go_back()