How to use the paperwork-backend.paperwork_backend.common.page.BasicPage function in paperwork-backend

def get(self, obj_id):
        """
        Get a document or a page using its ID
        Won't instantiate them if they are not yet available
        """
        if BasicPage.PAGE_ID_SEPARATOR in obj_id:
            (docid, page_nb) = obj_id.split(BasicPage.PAGE_ID_SEPARATOR)
            page_nb = int(page_nb)
            return self._docs_by_id[docid].pages[page_nb]
        return self._docs_by_id[obj_id]

def get(self, obj_id):
        """
        Get a document or a page using its ID
        Won't instantiate them if they are not yet available
        """
        if BasicPage.PAGE_ID_SEPARATOR in obj_id:
            (docid, page_nb) = obj_id.split(BasicPage.PAGE_ID_SEPARATOR)
            page_nb = int(page_nb)
            return self._docs_by_id[docid].pages[page_nb]
        return self._docs_by_id[obj_id]

input_el = zip(input_str, input_rects)
    for (is_split, group) in itertools.groupby(
        input_el,
        lambda x: splitter(x[0])
    ):
        if is_split:
            continue
        letters = ""
        rects = []
        for (letter, rect) in group:
            letters += letter
            rects.append(rect)
        yield(letters, rects)


class PdfPage(BasicPage):
    EXT_TXT = "txt"

    def __init__(self, doc, page_nb, on_disk_cache=True):
        super().__init__(doc, page_nb)
        self._size = None  # page size never change --> can be cached
        self.__boxes = None
        self._on_disk_cache = on_disk_cache

    def get_pdf_page(self, pdf=None):
        if pdf is None:
            pdf = self.doc.get_pdf()
        pdf_page = pdf.get_page(self.page_nb)
        return pdf_page

    @property
    def pdf_page(self):

import logging
import re

import PIL.Image
import pyocr
import pyocr.builders

from ..common.page import BasicPage
from ..util import image2surface


logger = logging.getLogger(__name__)


class ImgPage(BasicPage):

    """
    Represents a page. A page is a sub-element of ImgDoc.
    """

    EXT_IMG = "jpg"
    KEYWORD_HIGHLIGHT = 3
    FILE_REGEX = re.compile(
        BasicPage.FILE_PREFIX + "[1-9][0-9]*\." + EXT_IMG,
        re.IGNORECASE
    )

    can_edit = True

    def __init__(self, doc, page_nb=None):
        if page_nb is None:

def __init__(self, doc, page_nb=None):
        if page_nb is None:
            page_nb = doc.nb_pages
        BasicPage.__init__(self, doc, page_nb)