pRc, cWp = os.pipe() # parent-read-child, child-write-parent
cRp, pWc = os.pipe() # child-read-parent, parent-write-child
pRe, cWe = os.pipe() # parent-read-error, child-write-error
pRc, cWp = os.pipe() # parent-read-child, child-write-parent
cRp, pWc = os.pipe() # child-read-parent, parent-write-child
pRe, cWe = os.pipe() # parent-read-error, child-write-error