function is_deb {
    command_exists apt-get
}

function is_mac {
    [[ $(uname) == 'Darwin' ]]
}

function is_linux {
    [[ $(uname) == 'Linux' ]]
}

if is_mac; then

    function pkg-install() {
        brew install $1
    }

    function pkg-remove() {
        brew remove $1
    }

    function pkg-update() {
        brew update && brew upgrade
    }

elif is_deb; then

    function pkg-install() {
        sudo apt-get install $1
    }

    function pkg-remove() {
        sudo apt-get remove $1
    }

    function pkg-update() {
        sudo apt-get update && sudo apt-get upgrade
    }
    
fi