[[ -x $(whence -p nproc) ]] && {
  command nproc && {
    unfunction nproc
    return
  }
}
[[ -x $(which sysctl) ]] && {
  nproc() {
    sysctl -n hw.ncpu
  }
  nproc && return
}
# TODO other platforms
echo nproc: no implementation found >&2
nproc() {
  echo 2
}
nproc
# vim:ft=zsh