code: def is_valid_bibtex(reference):
      
      # str is necessary since pybtex seems to have an issue with unicode. The
      # filter expression removes all non-ASCII characters.
      sio = StringIO(remove_non_ascii(reference))
      parser = bibtex.Parser()
      errors.set_strict_mode(False)
      bib_data = parser.parse_stream(sio)
      return len(bib_data.entries) > 0
docs: Use pybtex to validate that a reference is in proper BibTeX format
  
      Args:
          reference: A String reference in BibTeX format.
  
      Returns:
          Boolean indicating if reference is valid bibtex.