To make Cha more seamless, I created the following command in my .zshrc:

chatgpt () { DEFAULT_MODEL="gpt-4-turbo-preview"

    # path to your OpenAI API key
    source /Users/mehmet/.custom/.env

    if [[ "$1" == "-f" && -n "$2" ]]; then
        cha -m $DEFAULT_MODEL -f "$2"
    elif [ $# -eq 0 ]; then
        cha --model $DEFAULT_MODEL
    else
        cha -m $DEFAULT_MODEL -s "$1"
    fi

    unset OPENAI_API_KEY
}