code: def pdfextract_dois(pdf_file):
      
      # Call pdf-extract on the PDF file
      references = pdfextract(pdf_file)
      # Parse the resulting XML
      root = ET.fromstring(references)
      plaintext_references = [e.text for e in root.iter("reference")]
      # Call the plaintext methods to fetch DOIs
      return plaintext.get_cited_dois(plaintext_references)
docs: Extract DOIs of references using \
              `pdfextract <https://github.com/CrossRef/pdfextract>`_.
  
      .. note::
  
          See ``libbmc.citations.pdf.pdfextract`` function as this one is just \
                  a wrapper around it.
          See ``libbmc.citations.plaintext.get_cited_dois`` as well for the \
                  returned value, as it is ultimately called by this function.
  
      :param pdf_file: Path to the PDF file to handle.
      :returns: A dict of cleaned plaintext citations and their associated DOI.