+if whichable apt; then
+ # ubuntu or debian or other apt-based OSes...
+ sudo apt install screen python3 python3-pip xserver-xorg xorg-docs
+ exit_on_error $PHASE_MESSAGE
+elif whichable yum; then
+ # rpm based with yum available...
+#new yums unvetted
+ sudo yum install screen python3 python3-pip xserver-xorg xorg-docs
+ exit_on_error $PHASE_MESSAGE
+elif [ ! -z "$IS_DARWIN" ]; then
+ # macos based...
+#hmmm: still working on these...
+ brew install screen python3 pip xserver-xorg xorg-docs
+ exit_on_error $PHASE_MESSAGE
+elif [ "$OS" == "Windows_NT" ]; then
+ # windows-based with cygwin (or we'll fail out).
+
+ if apt_cyg_finder; then
+echo need to fix apt cyg install list for extended apps somewhat.
+ apt-cyg install screen python3 pip3 xserver-xorg xorg-docs
+ exit_on_error $PHASE_MESSAGE
+ fi
+fi