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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 is_merged(sheet, row, column):
 """ Check if a row, column cell is a merged cell """

    for cell_range in sheet.merged_cells:
        row_low, row_high, column_low, column_high = cell_range
        if (row in range(row_low, row_high)) and \
                (column in range(column_low, column_high)):

            # TODO: IS NECESARY THIS IF?
            if ((column_high - column_low) < sheet.ncols - 1) and \
                    ((row_high - row_low) < sheet.nrows - 1):
                return (True, cell_range)

    return False