PREBUILT_DATA_DIR=data

checksum() {
    local file="$1"
    local sum="$2"
    echo "$file: verifying checksum..."
    echo "$sum  $file" | sha256sum -c
}

get_file() {
    local url="$1"
    local file="$2"
    local sum="$3"
    if [[ -f "$file" ]]
    then
        echo "$file: found"
    else
        echo "$file: not found, downloading..."
        wget "$url" -O "$file"
    fi
    checksum "$file" "$sum"
}