function __cmd.is_callable() {
    local cmd_type=`type -t $1`

    if [[ (-n $1) && (("$cmd_type" == @(builtin|function)) || ("$cmd_type" == @(file|alias) && -x `which $1`)) ]]; then
        echo 'YES we CAN use this command'
    else
        echo 'NO we CAN NOT use this command'
    fi
}