// When VBN, Theme
tregex:    S <1 (SBAR=begin <1 WHADVP <2 (S <: (VP=tr))) <2 /,/=comma <3 (__ << NP=arg)
operation: new arg tr
operation: prune begin comma

tregex:    S <1 (SBAR=begin <1 WHADVP <2 (S <: (VP=tr))) <2 (__ << NP=arg)
operation: new arg tr
operation: prune begin

// By VBG, Theme
tregex:    S <1 (PP=begin <2 (S <: (VP=tr))) <2 /,/=comma <3 (NP=arg)
operation: new arg tr
operation: prune begin comma

tregex:    S <1 (PP=begin <2 (S <: (VP=tr))) <2 (NP=arg)
operation: new arg tr
operation: prune begin