<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def __clean_doc_block(self):
 """ Cleans the DocBlock from leading and trailing white space and comment tokens. """

        # Return immediately if the DockBlock is empty.
        if not self._comment:
            return

        for i in range(1, len(self._comment) - 1):
            self._comment[i] = re.sub(r'^\s*\*', '', self._comment[i])

        self._comment[0] = re.sub(r'^\s*/\*\*', '', self._comment[0])

        self._comment[-1] = re.sub(r'\*/\s*$', '', self._comment[-1])

        for i, line in enumerate(self._comment):
            self._comment[i] = line.strip()

        self._comment = self.__remove_leading_empty_lines(self._comment)
        self._comment = self.__remove_trailing_empty_lines(self._comment)