zip2topojson() {
  NAME=$(basename $1 .zip)
  OUTPUT="$2"

  unzip -o $NAME.zip -d $NAME

  cd $NAME/

  [ -f $NAME.geo.json ] && rm $NAME.geo.json
  ogr2ogr -f GeoJSON -s_srs $NAME.prj -t_srs EPSG:4326 $NAME.geo.json $NAME.shp

  npx -p topojson -c "geo2topo -q 1e6 -o $NAME.topo.json $NAME=$NAME.geo.json"

  mv $NAME.topo.json $NAME.topo.json__old
  cat $NAME.topo.json__old | perl -pe 's/(\{"type":"(Multi)?Polygon")/\n  \1/g; s/(\]\}\},"arcs":)/\n\1/g' > $NAME.topo.json
  rm $NAME.topo.json__old

  cd ..

  mv "$NAME/$NAME.topo.json" "./$OUTPUT"

  rm -r $NAME/
}

##################################################################
# usage: zip2topojson reg2011_g.zip regions.topo.json
#
# `ogr2ogr` (`$ brew install gdal`), `geo2topo`, `npx`
# zip2topojson reg2011_g.zip regions.topo.json