More unknown Chinese problem book fuseki problems! I don't go into detail much, but just one possible variation illustrates the idea much, I think.
(;AB[dp]AB[cq]AB[cn]AB[pp]AB[qm]AW[dr]AW[fq]AW[hp]AW[jq]C[A or B?]LB[lq:A]LB[oq:B]AP[goproblems]
(;B[jl]C[This path is here just to make the problem view match the book view.])
(;B[oq]C[Yep! The corner is now cozily secure, and this makes efficient shape with the marked stone.RIGHT]MA[qm])
(;B[lq]C[Too close to white's strong group. The corner is still invadable.];W[nq]