How to use the bioframe.load_fasta function in bioframe

def test_frac_gc():
    pytest.importorskip("pysam")
    chromsizes = bioframe.read_chromsizes(testdir+"/test_data/test.chrom.sizes")
    fasta_records = bioframe.load_fasta(testdir+"/test_data/test.fa")

    unmapped_bp = (
        0
        == bioframe.frac_mapped(
            bioframe.binnify(chromsizes, 1), fasta_records, return_input=False
        ).values
    )
    assert np.isnan(
        bioframe.frac_gc(
            bioframe.binnify(chromsizes, 1),
            fasta_records,
            return_input=False,
            mapped_only=True,
        ).values[unmapped_bp]
    ).all()

def test_digest():
    pytest.importorskip("Bio")
    fasta_records = bioframe.load_fasta(testdir+"/test_data/test.fa")
    assert len(fasta_records) == 2
    ### no HindIII sites in the test.fa fasta records, so shouldn't change shape[0]
    assert bioframe.digest(fasta_records, "HindIII").shape == (2, 3)
    ### one DpnII site on chrTEST2, shape[0] should increase by one
    assert bioframe.digest(fasta_records, "DpnII").shape == (3, 3)
    ### DpnII site is on chrTEST2 position 3, first interval of chrTEST2 should end at 3
    assert bioframe.digest(fasta_records, "DpnII").iloc[1].end == 3

def test_frac_mapped():
    pytest.importorskip("pysam")
    chromsizes = bioframe.read_chromsizes(testdir+"/test_data/test.chrom.sizes")
    fasta_records = bioframe.load_fasta(testdir+"/test_data/test.fa")

    unmapped = np.array([1.0, 1.0, 1.0, 1.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0, 0.0, 0.0])
    assert (
        unmapped
        == bioframe.frac_mapped(
            bioframe.binnify(chromsizes, 1), fasta_records, return_input=False
        ).values
    ).all()

    unmapped = np.array([0.8, 0.8, 0])
    assert (
        unmapped
        == bioframe.frac_mapped(
            bioframe.binnify(chromsizes, 5), fasta_records, return_input=False
        ).values
    ).all()