How to use the snps.resources.ReferenceSequence function in snps

def test_reference_sequence_generic_load_sequence(self):
        with open("tests/input/generic.fa", "rb") as f_in:
            with atomic_write(
                "tests/input/generic.fa.gz", mode="wb", overwrite=True
            ) as f_out:
                with gzip.open(f_out, "wb") as f_gzip:
                    shutil.copyfileobj(f_in, f_gzip)

        seq = ReferenceSequence(ID="1", path="tests/input/generic.fa.gz")
        assert seq.ID == "1"
        assert seq.chrom == "1"
        assert seq.path == "tests/input/generic.fa.gz"
        np.testing.assert_array_equal(
            seq.sequence,
            np.array(
                bytearray(
                    "NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNAGGCCGGACNNNNNNNN",
                    encoding="utf-8",
                    errors="strict",
                ),
                dtype=np.uint8,
            ),
        )
        assert list("AGGCCGGAC") == list(map(chr, seq.sequence[100:109]))
        assert seq.md5 == "6ac6176535ad0e38aba2d05d786c39b6"

def test_save_snps_vcf(self):
        s = SNPs("tests/input/testvcf.vcf")

        r = Resources()
        r._reference_sequences["GRCh37"] = {}

        with tempfile.TemporaryDirectory() as tmpdir:
            dest = os.path.join(tmpdir, "generic.fa.gz")
            gzip_file("tests/input/generic.fa", dest)

            seq = ReferenceSequence(ID="1", path=dest)

            r._reference_sequences["GRCh37"]["1"] = seq

            self.assertEqual(
                os.path.relpath(s.save_snps(vcf=True)), "output/vcf_GRCh37.vcf"
            )

        self.run_parsing_tests_vcf("output/vcf_GRCh37.vcf")

def test_save_snps_vcf_phased(self):
        # read phased data
        s = SNPs("tests/input/testvcf_phased.vcf")

        # setup resource to use test FASTA reference sequence
        r = Resources()
        r._reference_sequences["GRCh37"] = {}

        with tempfile.TemporaryDirectory() as tmpdir:
            dest = os.path.join(tmpdir, "generic.fa.gz")
            gzip_file("tests/input/generic.fa", dest)

            seq = ReferenceSequence(ID="1", path=dest)

            r._reference_sequences["GRCh37"]["1"] = seq

            # save phased data to VCF
            self.assertEqual(
                os.path.relpath(s.save_snps(vcf=True)), "output/vcf_GRCh37.vcf"
            )

        # read saved VCF
        self.run_parsing_tests_vcf("output/vcf_GRCh37.vcf", phased=True)