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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 _parse_udiff(self):
 """ Parse the diff an return data for the template. """

        lineiter = self.lines
        files = []
        try:
            line = lineiter.next()
            # skip first context
            skipfirst = True
            while 1:
                # continue until we found the old file
                if not line.startswith('--- '):
                    line = lineiter.next()
                    continue

                chunks = []
                filename, old_rev, new_rev = \
                    self._extract_rev(line, lineiter.next())
                files.append({
                    'filename':         filename,
                    'old_revision':     old_rev,
                    'new_revision':     new_rev,
                    'chunks':           chunks
                })

                line = lineiter.next()
                while line:
                    match = self._chunk_re.match(line)
                    if not match:
                        break

                    lines = []
                    chunks.append(lines)

                    old_line, old_end, new_line, new_end = \
                        [int(x or 1) for x in match.groups()[:-1]]
                    old_line -= 1
                    new_line -= 1
                    context = len(match.groups()) == 5
                    old_end += old_line
                    new_end += new_line

                    if context:
                        if not skipfirst:
                            lines.append({
                                'old_lineno': '...',
                                'new_lineno': '...',
                                'action': 'context',
                                'line': line,
                            })
                        else:
                            skipfirst = False

                    line = lineiter.next()
                    while old_line < old_end or new_line < new_end:
                        if line:
                            command, line = line[0], line[1:]
                        else:
                            command = ' '
                        affects_old = affects_new = False

                        # ignore those if we don't expect them
                        if command in '#@':
                            continue
                        elif command == '+':
                            affects_new = True
                            action = 'add'
                        elif command == '-':
                            affects_old = True
                            action = 'del'
                        else:
                            affects_old = affects_new = True
                            action = 'unmod'

                        old_line += affects_old
                        new_line += affects_new
                        lines.append({
                            'old_lineno':   affects_old and old_line or '',
                            'new_lineno':   affects_new and new_line or '',
                            'action':       action,
                            'line':         line
                        })
                        line = lineiter.next()

        except StopIteration:
            pass

        # highlight inline changes
        for file in files:
            for chunk in chunks:
                lineiter = iter(chunk)
                #first = True
                try:
                    while 1:
                        line = lineiter.next()
                        if line['action'] != 'unmod':
                            nextline = lineiter.next()
                            if nextline['action'] == 'unmod' or \
                               nextline['action'] == line['action']:
                                continue
                            self.differ(line, nextline)
                except StopIteration:
                    pass

        return files