use `wget` if it's available and curl isn't

  popd >&4

}

if type curl &>/dev/null; then

get() { curl "$@" ;}

elif type wget &>/dev/null; then

get() { wget -O- "$@" ;}

else

get() { echo "curl or wget is required" >&2; exit 1 ;}

fi

fetch_tarball() {

  local package_name="$1"

  local package_url="$2"

  echo "Downloading ${package_url}..." >&2

  { curl "$package_url" > "${package_name}.tar.gz"

  { get "$package_url" > "${package_name}.tar.gz"

    tar xzvf "${package_name}.tar.gz"

  } >&4 2>&1

}