have cal || have ncal || return

_cal()
{
    local cur prev words cword
    _init_completion || return

    case $prev in
        -m)
            if [[ $OSTYPE == *bsd* ]]; then
                COMPREPLY=( $( compgen -W '{1..12}' -- "$cur" ) )
                return
            fi
            ;;
        -s)
            [[ $OSTYPE == *bsd* ]] && return
            ;;
        -A|-B|-d|-H)
            return
            ;;
    esac

    if [[ $cur == -* ]]; then
        COMPREPLY=( $( compgen -W '$( _parse_usage "$1" )' -- "$cur" ) )
        return
    fi

    local args
    _count_args
    [[ $args -eq 1 ]] && COMPREPLY=( $( compgen -W '{1..12}' -- "$cur" ) )
} &&
complete -F _cal cal ncal

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