docs: def iter_genotypes(self):
          """Iterates on available markers.
  
          Returns:
              Genotypes instances.
  
          """
          # Seeking at the beginning of the file
          self._impute2_file.seek(0)
  
          # Parsing each lines of the IMPUTE2 file
          for i, line in enumerate(self._impute2_file):
              genotypes = self._parse_impute2_line(line)
  
              variant_info = None
              if self.has_index:
                  variant_info = self._impute2_index.iloc[i, :]
              self._fix_genotypes_object(genotypes, variant_info)
  
              yield genotypes