code: def get_breakpoints(self, lineno):
          
          try:
              firstlineno, actual_lno = self.bdb_module.get_actual_bp(lineno)
          except BdbSourceError:
              return []
          if firstlineno not in self:
              return []
          code_bps = self[firstlineno]
          if actual_lno not in code_bps:
              return []
          return [bp for bp in sorted(code_bps[actual_lno],
                      key=attrgetter('number')) if bp.line == lineno]
docs: Return the list of breakpoints set at lineno.