Return position of end of cell marker, and position
        of first line after cell

def find_cell_end(self, lines):
        """Return position of end of cell marker, and position
        of first line after cell"""

        if self.metadata and 'cell_type' in self.metadata:
            self.cell_type = self.metadata.pop('cell_type')
        else:
            self.cell_type = 'code'

        next_cell = len(lines)
        for i, line in enumerate(lines):
            if i > 0 and (self.start_code_re.match(line) or self.alternative_start_code_re.match(line)):
                next_cell = i
                break

        if last_two_lines_blank(lines[:next_cell]):
            return next_cell - 2, next_cell, False
        if next_cell > 0 and _BLANK_LINE.match(lines[next_cell - 1]):
            return next_cell - 1, next_cell, False
        return next_cell, next_cell, False