In words, give step-by-step directions for drawing the mechanism for the reaction of 1,3-butadiene with HBr.Give explicit information about where "electron-pushing" arrows should begin and end, what new bonds are formed or broken, what atoms have non-zero formal charges, etc. Describe all three steps of the reaction: (a) protonation of carbon 1 (b) the formation of an allylic, resonance-stabilized carbocation intermediate - explain what this is and which carbons have partial positive charge, and (c) attack of Br- to give the 1,2 and 1,4 product.