How to use the ocrmypdf.exec.tesseract.v4 function in ocrmypdf

#
# OCRmyPDF is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with OCRmyPDF.  If not, see .

import pytest
from ocrmypdf.exceptions import ExitCode
from ocrmypdf.exec import tesseract


# Skip all tests in this file if not tesseract 3
pytestmark = pytest.mark.skipif(tesseract.v4(),
                                reason="tesseract 3.x required")


@pytest.mark.skipif(tesseract.has_textonly_pdf(),
                    reason="check that missing dep is reported on old tess3")
def test_textonly_pdf_on_older_tess3(resources, no_outpdf):
    p, _, _ = pytest.helpers.run_ocrmypdf(
        resources / 'linn.pdf',
        no_outpdf, '--pdf-renderer', 'sandwich')

    assert p.returncode == ExitCode.missing_dependency


@pytest.mark.skipif(not tesseract.has_textonly_pdf(),
                    reason="check that feature is exercised on new test3")
def test_textonly_pdf_on_newer_tess3(resources, no_outpdf):

def test_tesseract_v4():
    assert tesseract.v4()