Wax_utils.PagerSourceuse f calls f with standard output, routed through a pager when it is a terminal. Read any standard-input content before calling use: the pager takes over the terminal as soon as it starts (raw mode, echo off), which would hide input still being typed.
Whether output written through use may carry ANSI escape sequences: either it is not paged at all, or the pager renders them (less -R; a user-chosen $PAGER is trusted to). Windows' default more passes them through raw, which legacy consoles display as garbage.