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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def summarise_pdfs(pdfs):
 """ Collate the first page from each of the PDFs provided into a single PDF. :param pdfs: The contents of several PDF files. :type pdfs: list of str :returns: The contents of single PDF, which can be written directly to disk. """


    # Ignore None.
    print('Summarising {0} articles ({1} had errors)'.format(
        len(pdfs), pdfs.count(None)))
    pdfs = [_ for _ in pdfs if _ is not None]

    summary = PdfFileWriter()
    for pdf in pdfs:
        summary.addPage(PdfFileReader(StringIO(pdf)).getPage(0))
    return summary