set-selective-display
set-selective-display is an interactive compiled Lisp function in `simple.el
'.
It is bound to C-x $.
(set-selective-display ARG
)
Set `selective-display' to ARG; clear it if no arg.
When the value of `selective-display' is a number > 0,
lines whose indentation is >= that value are not displayed.
The variable `selective-display' has a separate value for each buffer.