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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 next(self):
 """Return next line without end of line marker or raise StopIteration."""

    try:
      next_line = next(self._f)
    except StopIteration:
      self._FinalCheck()
      raise

    self._line_number += 1
    m_eol = re.search(r"[\x0a\x0d]*$", next_line)
    if m_eol.group() == "\x0d\x0a":
      self._crlf += 1
      if self._crlf <= 5:
        self._crlf_examples.append(self._line_number)
    elif m_eol.group() == "\x0a":
      self._lf += 1
      if self._lf <= 5:
        self._lf_examples.append(self._line_number)
    elif m_eol.group() == "":
      # Should only happen at the end of the file
      try:
        next(self._f)
        raise RuntimeError("Unexpected row without new line sequence")
      except StopIteration:
        # Will be raised again when EndOfLineChecker.next() is next called
        pass
    else:
      self._problems.InvalidLineEnd(
        codecs.getencoder('string_escape')(m_eol.group())[0],
        (self._name, self._line_number))
    next_line_contents = next_line[0:m_eol.start()]
    for seq, name in INVALID_LINE_SEPARATOR_UTF8.items():
      if next_line_contents.find(seq) != -1:
        self._problems.OtherProblem(
          "Line contains %s" % name,
          context=(self._name, self._line_number))
    return next_line_contents