code: def __annotate_sequence_with_quality(seq, q_line_parts):
    
    if q_line_parts[1] != seq.name:
      raise MAFError("trying to populate meta data for sequence " + seq.name +
                     " with q-line information for " +
                     str(q_line_parts[1]) + "; maflormed MAF file?")
    if len(q_line_parts[2]) != len(seq):
      raise MAFError("trying to populate quality meta data for sequence with " +
                     "length " + str(len(seq)) + " using quality line with " +
                     "length " + str(len(q_line_parts[2])) + "; malformed " +
                     "MAF file?")
    seq.meta_data[QUALITY_META_KEY] = q_line_parts[2]
docs: Extract meta data from pre-tokenized maf q-line and populate sequence.
  
    q -- quality information about an aligned base in a species. Two fields after
         the 'q': the source name and a single digit for each nucleotide in its
         sequence (0-9 or F, or - to indicate a gap).