Iterates on available markers.

        Returns:
            Genotypes instances.

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