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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def diff(before, after, check_modified=False):
 """Diff two sequences of comparable objects. The result of this function is a list of dictionaries containing values in ``before`` or ``after`` with a ``state`` of either 'unchanged', 'added', 'deleted', or 'modified'. [{'state': 'deleted', 'value': 'a'}, {'state': 'unchanged', 'value': 'b'}, {'state': 'unchanged', 'value': 'c'}, {'state': 'added', 'value': 'd'}] Parameters before : iterable An iterable containing values to be used as the baseline version. after : iterable An iterable containing values to be compared against the baseline. check_modified : bool Whether or not to check for modifiedness. Returns ------- diff_items : A list of dictionaries containing diff information. """


    # The grid will be empty if `before` or `after` are
    # empty; this will violate the assumptions made in the rest
    # of this function.
    # If this is the case, we know what the result of the diff is
    # anyways: the contents of the other, non-empty input.
    if len(before) == 0:
        return [
            {'state': 'added', 'value': v}
            for v in after
        ]
    elif len(after) == 0:
        return [
            {'state': 'deleted', 'value': v}
            for v in before
        ]

    grid = create_grid(before, after)

    nrows = len(grid[0])
    ncols = len(grid)
    dps = diff_points(grid)
    result = []
    for kind, col, row in dps:
        if kind == 'unchanged':
            value = before[col]
            result.append({
                'state': kind,
                'value': value,
            })
        elif kind == 'deleted':
            assert col < ncols
            value = before[col]
            result.append({
                'state': kind,
                'value': value,
            })
        elif kind == 'added':
            assert row < nrows
            value = after[row]
            result.append({
                'state': kind,
                'value': value,
            })
        elif check_modified and kind == 'modified':
            result.append({
                'state': kind,
                'originalvalue': before[col],
                'modifiedvalue': after[row],
            })
        elif (not check_modified) and kind == 'modified':
            result.append({
                'state': 'deleted',
                'value': before[col],
            })
            result.append({
                'state': 'added',
                'value': after[row],
            })
        else:
            raise Exception('We should not be here.')
    return result