Simplify setting of transition mode

99bottles.sh

         echo "Go to the store and buy some more"
         nb=ninety-nine
     else
-        echo "$BreakLine"
+        echo "$TransitionLine"
         nb=$(pred "$nb")
     fi
     echo "$nb bottles of beer on the wall"
 }
 
 main() {
-    local BreakLine             # bottle-break (or not) line
-    local standard_break_line   # ^^ standard variant
-    local wasteful_break_line   # ^^ wasteful (bottle breaks) variant
-    local nb            # beginning number
-    standard_break_line="Take one down and pass it around"
-    wasteful_break_line="If one of those bottles should happen to fall"
-    BreakLine=$(
-        [ "$1" = --careless ] \
-         && echo "$wasteful_break_line" \
-         || echo "$standard_break_line"
+    local TransitionLine    # transition line between verses
+    local nb                # beginning number
+    local mode=standard     # transition mode
+    while true; do case $1 in
+        --careless)     mode=careless; shift ;;
+        *)              break ;;
+    esac done
+    TransitionLine=$(
+        case $mode in
+            standard)   echo "Take one down and pass it around" ;;
+            careless)   echo "If one of those bottles should happen to fall" ;;
+        esac
     )
     nb=ninety-nine
     while [ -n "$nb" ]; do