title: Merge 2 pdf files giving me an empty pdf
body: <p>I am using the following standard code:</p>
  
  <pre><code># importing required modules
  import PyPDF2
  
  def PDFmerge(pdfs, output):
      # creating pdf file merger object
      pdfMerger = PyPDF2.PdfFileMerger()
  
      # appending pdfs one by one
      for pdf in pdfs:
          with open(pdf, 'rb') as f:
              pdfMerger.append(f)
  
      # writing combined pdf to output pdf file
      with open(output, 'wb') as f:
          pdfMerger.write(f)
  
  def main():
      # pdf files to merge
      pdfs = ['example.pdf', 'rotated_example.pdf']
  
      # output pdf file name
      output  = 'combined_example.pdf'
  
      # calling pdf merge function
      PDFmerge(pdfs = pdfs, output = output)
  
  if __name__ == "__main__":
      # calling the main function
      main()
  </code></pre>
  
  <p>But when I call this with my 2 pdf files (which just contain some text), it produces an empty pdf file, I am wondering how this may be caused?</p>