def split_col_row(ref):
    """Split the letter and number components of a cell reference.

    Examples:
        >>> split_col_row('A1')
        ('A', 1)
        >>> split_col_row('B100')
        ('B', 100)
        >>> split_col_row('CC12')
        ('CC', 12)
    """
    head = ref.rstrip("0123456789")
    tail = ref[len(head) :]
    return head, int(tail)