class_docstr: This class allows to capture writes to FD1 and FD2
  and may connect a NULL file to FD0 (and prevent
  reads from sys.stdin).  If any of the 0,1,2 file descriptors
  is invalid it will not be captured.
code: def startall(self):
      if hasattr(self, "in_"):
          self.in_.start()
      if hasattr(self, "out"):
          self.out.start()
      if hasattr(self, "err"):
          self.err.start()
  
imports: import os
  import sys
  import py
  import tempfile
label_desc: Use image node_id 3 for calling the StdCaptureFD obj's underlying member method code with example usage: obj.startall() without return types