code: def drop_columns(records, slices):
      
      for record in records:
          # Generate a set of indices to remove
          drop = set(i for slice in slices
                     for i in range(*slice.indices(len(record))))
          keep = [i not in drop for i in range(len(record))]
          record.seq = Seq(''.join(itertools.compress(record.seq, keep)), record.seq.alphabet)
          yield record
docs: Drop all columns present in ``slices`` from records