219 lines
8.1 KiB
Python
219 lines
8.1 KiB
Python
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import itertools
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import logging
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from typing import Any, BinaryIO, Container, Dict, Iterator, List, Optional, Set, Tuple
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from pdfminer import settings
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from pdfminer.pdfdocument import (
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PDFDocument,
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PDFNoPageLabels,
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PDFTextExtractionNotAllowed,
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)
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from pdfminer.pdfexceptions import PDFObjectNotFound, PDFValueError
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from pdfminer.pdfparser import PDFParser
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from pdfminer.pdftypes import dict_value, int_value, list_value, resolve1
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from pdfminer.psparser import LIT
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from pdfminer.utils import Rect, parse_rect
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log = logging.getLogger(__name__)
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# some predefined literals and keywords.
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LITERAL_PAGE = LIT("Page")
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LITERAL_PAGES = LIT("Pages")
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class PDFPage:
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"""An object that holds the information about a page.
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A PDFPage object is merely a convenience class that has a set
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of keys and values, which describe the properties of a page
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and point to its contents.
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Attributes
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----------
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doc: a PDFDocument object.
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pageid: any Python object that can uniquely identify the page.
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attrs: a dictionary of page attributes.
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contents: a list of PDFStream objects that represents the page content.
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lastmod: the last modified time of the page.
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resources: a dictionary of resources used by the page.
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mediabox: the physical size of the page.
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cropbox: the crop rectangle of the page.
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rotate: the page rotation (in degree).
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annots: the page annotations.
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beads: a chain that represents natural reading order.
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label: the page's label (typically, the logical page number).
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"""
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def __init__(
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self,
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doc: PDFDocument,
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pageid: object,
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attrs: object,
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label: Optional[str],
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) -> None:
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"""Initialize a page object.
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doc: a PDFDocument object.
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pageid: any Python object that can uniquely identify the page.
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attrs: a dictionary of page attributes.
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label: page label string.
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"""
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self.doc = doc
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self.pageid = pageid
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self.attrs = dict_value(attrs)
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self.label = label
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self.lastmod = resolve1(self.attrs.get("LastModified"))
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self.resources: Dict[object, object] = resolve1(
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self.attrs.get("Resources", dict()),
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)
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self.mediabox = self._parse_mediabox(self.attrs.get("MediaBox"))
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self.cropbox = self._parse_cropbox(self.attrs.get("CropBox"), self.mediabox)
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self.contents = self._parse_contents(self.attrs.get("Contents"))
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self.rotate = (int_value(self.attrs.get("Rotate", 0)) + 360) % 360
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self.annots = self.attrs.get("Annots")
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self.beads = self.attrs.get("B")
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def __repr__(self) -> str:
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return f"<PDFPage: Resources={self.resources!r}, MediaBox={self.mediabox!r}>"
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INHERITABLE_ATTRS = {"Resources", "MediaBox", "CropBox", "Rotate"}
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@classmethod
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def create_pages(cls, document: PDFDocument) -> Iterator["PDFPage"]:
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def depth_first_search(
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obj: Any,
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parent: Dict[str, Any],
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visited: Optional[Set[Any]] = None,
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) -> Iterator[Tuple[int, Dict[Any, Dict[Any, Any]]]]:
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if isinstance(obj, int):
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object_id = obj
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object_properties = dict_value(document.getobj(object_id)).copy()
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else:
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# This looks broken. obj.objid means obj could be either
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# PDFObjRef or PDFStream, but neither is valid for dict_value.
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object_id = obj.objid # type: ignore[attr-defined]
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object_properties = dict_value(obj).copy()
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# Avoid recursion errors by keeping track of visited nodes
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if visited is None:
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visited = set()
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if object_id in visited:
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return
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visited.add(object_id)
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for k, v in parent.items():
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if k in cls.INHERITABLE_ATTRS and k not in object_properties:
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object_properties[k] = v
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object_type = object_properties.get("Type")
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if object_type is None and not settings.STRICT: # See #64
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object_type = object_properties.get("type")
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if object_type is LITERAL_PAGES and "Kids" in object_properties:
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log.debug("Pages: Kids=%r", object_properties["Kids"])
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for child in list_value(object_properties["Kids"]):
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yield from depth_first_search(child, object_properties, visited)
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elif object_type is LITERAL_PAGE:
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log.debug("Page: %r", object_properties)
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yield (object_id, object_properties)
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try:
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page_labels: Iterator[Optional[str]] = document.get_page_labels()
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except PDFNoPageLabels:
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page_labels = itertools.repeat(None)
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pages = False
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if "Pages" in document.catalog:
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objects = depth_first_search(document.catalog["Pages"], document.catalog)
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for objid, tree in objects:
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yield cls(document, objid, tree, next(page_labels))
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pages = True
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if not pages:
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# fallback when /Pages is missing.
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for xref in document.xrefs:
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for objid in xref.get_objids():
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try:
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obj = document.getobj(objid)
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if isinstance(obj, dict) and obj.get("Type") is LITERAL_PAGE:
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yield cls(document, objid, obj, next(page_labels))
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except PDFObjectNotFound:
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pass
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@classmethod
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def get_pages(
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cls,
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fp: BinaryIO,
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pagenos: Optional[Container[int]] = None,
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maxpages: int = 0,
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password: str = "",
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caching: bool = True,
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check_extractable: bool = False,
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) -> Iterator["PDFPage"]:
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# Create a PDF parser object associated with the file object.
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parser = PDFParser(fp)
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# Create a PDF document object that stores the document structure.
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doc = PDFDocument(parser, password=password, caching=caching)
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# Check if the document allows text extraction.
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# If not, warn the user and proceed.
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if not doc.is_extractable:
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if check_extractable:
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error_msg = "Text extraction is not allowed: %r" % fp
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raise PDFTextExtractionNotAllowed(error_msg)
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else:
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warning_msg = (
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"The PDF %r contains a metadata field "
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"indicating that it should not allow "
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"text extraction. Ignoring this field "
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"and proceeding. Use the check_extractable "
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"if you want to raise an error in this case" % fp
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)
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log.warning(warning_msg)
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# Process each page contained in the document.
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for pageno, page in enumerate(cls.create_pages(doc)):
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if pagenos and (pageno not in pagenos):
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continue
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yield page
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if maxpages and maxpages <= pageno + 1:
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break
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def _parse_mediabox(self, value: Any) -> Rect:
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us_letter = (0.0, 0.0, 612.0, 792.0)
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if value is None:
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log.warning(
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"MediaBox missing from /Page (and not inherited), "
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"defaulting to US Letter"
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)
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return us_letter
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try:
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return parse_rect(resolve1(val) for val in resolve1(value))
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except PDFValueError:
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log.warning("Invalid MediaBox in /Page, defaulting to US Letter")
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return us_letter
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def _parse_cropbox(self, value: Any, mediabox: Rect) -> Rect:
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if value is None:
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log.warning("CropBox missing from /Page, defaulting to MediaBox")
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return mediabox
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try:
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return parse_rect(resolve1(val) for val in resolve1(value))
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except PDFValueError:
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log.warning("Invalid CropBox in /Page, defaulting to MediaBox")
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return mediabox
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def _parse_contents(self, value: Any) -> List[Any]:
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contents: List[Any] = []
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if value is not None:
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contents = resolve1(value)
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if not isinstance(contents, list):
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contents = [contents]
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return contents
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