Draw a polyline ,before complete draw,how can i go back the last single click

[xiaoyunnsongb]

Hello every superiors:

       Now I use esri/toolbars/edit  to draw  a polyline,  now  I click but  this is wrong ，how can I go back the last single click

pic2------> pic1

pic2

pic1

[xiaoyunnsongb]

now I have single click , how can I undo this  single ，how to develop to realize this function ，thanks very much.