def dessine_tableau(tableau, titres=None):
    lengths = []
    if titres:
        tableau.insert(0, titres)
    nb_columns = len(tableau[0])
    nb_rows = len(tableau)
    for i in range(nb_columns):
        lengths.append(max([len(str(x[i])) for x in tableau]))
    
    print('╭', end='')
    for col in range(nb_columns):
        print('─'*lengths[col], end='')
        if not col+1==nb_columns:
            print('┬', end='')
    print('╮')

    if titres:
        print('│', end='')
        for col, cell in enumerate(tableau[0]):
            width = lengths[col]
            print(f"{cell: <{width}}", end='│')
        print()
        print('┝', end='')
        for col in range(nb_columns):
            print('━'*lengths[col], end='')
            if not col+1==nb_columns:
                print('┿', end='')
            else:
                print('┥')
    
    starting_row = 1 if titres else 0
    for row in tableau[starting_row:]:
        if row:
            print('│', end='')
            for col, cell in enumerate(row):
                width = lengths[col]
                print(f"{cell: <{width}}", end='│')
            print()
    
    print('╰', end='')
    for col in range(nb_columns):
        print('─'*lengths[col], end='')
        if not col+1==nb_columns:
            print('┴', end='')
    print('╯')