demos: extract some of run_scripts.sh to a function

This allows `run_scripts.sh | pager` to work.

demos/run_scripts.sh

@@ -31,14 +31,19 @@ GIT_CONFIG_GLOBAL=$(mktemp --tmpdir gitconfig-XXXX)
 export GIT_CONFIG_GLOBAL
 git_config "$GIT_CONFIG_GLOBAL"
 
-for script in "$@"; do
+run_script_through_term_transcript_and_pipe_result_to_stderr() {
+  script="$1"
   script_base="${script%.sh}"
   script_base="${script_base#demo_}"
   # We use `term-transcript capture` instead of `term-transcript exec` so that
   # we can show the output of the script via `tee`.
   (bash "$script" || (echo "SCRIPT FAILED WITH EXIT CODE $?"; false)) 2>&1 | \
     tee /dev/stderr | \
     term-transcript capture --no-inputs --pure-svg --out "$script_base".svg "$script_base"
+}
+
+for script in "$@"; do
+  run_script_through_term_transcript_and_pipe_result_to_stderr "$script" 2>&1
   # Resize to 700 width and any height
   which convert > /dev/null \
     && convert  -resize 700x10000 -colors 50 -background black \