code: def fasta_stats(self):
          
          for sample in self.metadata:
              # Initialise variables to store appropriate values parsed from contig records
              contig_lengths = list()
              fasta_sequence = str()
              for contig, record in sample[self.analysistype].record_dict.items():
                  # Append the length of the contig to the list
                  contig_lengths.append(len(record.seq))
                  # Add the contig sequence to the string
                  fasta_sequence += record.seq
              # Set the reverse sorted (e.g. largest to smallest) list of contig sizes as the value
              sample[self.analysistype].contig_lengths = sorted(contig_lengths, reverse=True)
              try:
                  # Calculate the GC% of the total genome sequence using GC - format to have two decimal places
                  sample[self.analysistype].gc = float('{:0.2f}'.format(GC(fasta_sequence)))
              except TypeError:
                  sample[self.analysistype].gc = 'NA'
docs: Parse the lengths of all contigs for each sample, as well as the total GC%