def mark_coverage(percentage):
    """Return a mark from A to F based on the passed tests percentage.

    :param percentage: Percentage of passed unit tests.
    :type percentage: float
    :return: Mark from A to F.
    :rtype: str
    """
    mark_table = {
        "A": (90, 101),
        "B": (80, 90),
        "C": (70, 80),
        "D": (60, 70),
        "F": (0, 59),
    }
    for mark, mark_range in mark_table.items():
        if int(percentage) in range(*mark_range):
            return mark