code: def signature(self):
          "Instance file name"
          kw = self.get_params()
          keys = sorted(kw.keys())
          l = []
          for k in keys:
              n = k[0] + k[-1]
              v = kw[k]
              if k == 'function_set':
                  v = "_".join([x.__name__[0] +
                                x.__name__[-1] +
                                str(x.nargs) for x in kw[k]])
              elif k == 'population_class':
                  v = kw[k].__name__
              else:
                  v = str(v)
              l.append('{0}_{1}'.format(n, v))
          return '-'.join(lf signature(self):
          "Instance file name"
          kw = self.get_params()
          keys = sorted(kw.keys())
          l = []
          for k in keys:
              n = k[0] + k[-1]
              v = kw[k]
              if k == 'function_set':
                  v = "_".join([x.__name__[0] +
                                x.__name__[-1] +
                                str(x.nargs) for x in kw[k]])
              elif k == 'population_class':
                  v = kw[k].__name__
              else:
                  v = str(v)
              l.append('{0}_{1}'.format(n, v))
          return '-'.join(l)
docs: Instance file name