code: def from_block(cls, block):
          
          rseqs = cma.realign_seqs(block)
          records = (SeqRecord(Seq(rseq, extended_protein),
                      id=bseq['id'],
                      description=bseq['description'],
                      dbxrefs=bseq['dbxrefs'].values(),   # list of strings
                      annotations=dict(
                          index=bseq['index'],
                          length=bseq['length'],
                          dbxrefs=bseq['dbxrefs'],
                          phylum=bseq['phylum'],
                          taxchar=bseq['taxchar'],
                          head_seq=bseq['head_seq'],
                          tail_seq=bseq['tail_seq'],
                          head_len=bseq['head_len'],
                          tail_len=bseq['tail_len'],      # dict
                          ),
                      # ENH: annotate with conservation levels
                      # letter_annotations=bseq['x'],
                      )
                  for bseq, rseq in zip(block['sequences'], rseqs))
          return cls(records,
                  # CMA attributes
                  # block['one'],
                  block['level'],
                  block['name'],
                  block['params'],
                  block['query_length'],
                  block['query_chars'],
                  )
docs: Instantiate this class given a raw block (see parse_raw).