code: def get_consensus(block):
      
      from collections import Counter
  
      # Take aligned (non-insert) chars from all rows; transpose
      columns = zip(*[[c for c in row['seq'] if not c.islower()]
                      for row in block['sequences']])
      cons_chars = [Counter(col).most_common()[0][0] for col in columns]
      cons_chars = [c if c != '-' else 'X' for c in cons_chars]
      assert len(cons_chars) == block['query_length']
      cons_sequence = {
          'index': 1,
          'id': 'consensus',
          'description': '',
          'dbxrefs': {},
          'phylum': '',
          'taxchar': '',
          'head_len': None,
          'tail_len': None,
          'head_seq': '',
          'tail_seq': '',
          'length': block['query_length'],
          'seq': ''.join(cons_chars),
      }
      return cons_sequence
docs: Calculate a simple consensus sequence for the block.