docs: def read_tsv(cls, path, encoding='utf-8'):
          """Read a gene set database from a tab-delimited text file.
  
          Parameters
          ----------
          path: str
              The path name of the the file.
          encoding: str
              The encoding of the text file.
  
          Returns
          -------
          None
          """
          gene_sets = []
          n = 0
          with open(path, 'rb') as fh:
              reader = csv.reader(fh, dialect='excel-tab', encoding=encoding)
              for l in reader:
                  n += 1
                  gs = GeneSet.from_list(l)
                  gene_sets.append(gs)
          logger.debug('Read %d gene sets.', n)
          logger.debug('Size of gene set list: %d', len(gene_sets))
          return cls(gene_sets)