code: def _code(self):
          
          icode, tcode = '', '' # imports, task code
          icall, pcall = '', '' # imap calls, piper calls
          tdone, idone = [], [] # task done, imap done
  
          for piper in self:
              p = piper
              w = piper.worker
              i = piper.imap
              in_ = i.name if hasattr(i, 'name') else False
              if in_ and in_ not in idone:
                  icall += I_SIG % (in_, i.worker_type, i.worker_num, i.stride, \
                                    i.buffer, i.ordered, i.skip, in_)
                  idone.append(in_)
              ws = W_SIG % (",".join([t.__name__ for t in w.task]), w.args, w.kwargs)
              pcall += P_SIG % (p.name, ws, in_, p.consume, p.produce, p.spawn, \
                                p.timeout, p.branch, p.debug, p.name, p.track)
              for t in w.task:
                  if (t in tdone) or not t:
                      continue
                  tm, tn = t.__module__, t.__name__
                  if (tm == '__builtin__') or hasattr(p, tn):
                      continue
                  if tm == '__main__' or tm == self.filename:
                      tcode += getsource(t)
                  else:
                      icode += 'from %s import %s\n' % (tm, tn)
                  tdone.append(t)
  
          pipers = [p.name for p in self]
          pipers = '[%s]' % ", ".join(pipers)
          pipes = [L_SIG % (d.name, s.name) for s, d in self.edges()]
          pipes = '[%s]' % ", ".join(pipes)                           # pipes
          xtras = [str(self[p].xtra) for p in self]
          xtras = '[%s]' % ",".join(xtras)                            # node xtra
          return (icode, tcode, icall, pcall, pipers, xtras, pipes)
docs: (internal) generates imports, code and runtime calls to save a pipeline.