_sb() {
    local cur prev opts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD - 1]}"
    opts="activate deactivate list"

    if [[ ${prev} == "activate" || ${prev} == "deactivate" ]]; then
        COMPREPLY=($(compgen -f -- "${cur}"))
        return 0
    fi

    if [[ ${COMP_CWORD} == 1 ]]; then
        COMPREPLY=($(compgen -W "${opts}" -- ${cur}))
        return 0
    fi
}
complete -F _sb sb