what they 're doing is a matter of plumbing arrangements and mind games , of no erotic or sensuous charge . 
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(ROOT (S (SBAR (WHNP (WP )) (S (NP (PRP )) (VP (VBP ) (VP (VBG ))))) (VP (VBZ ) (NP (NP (DT ) (NN )) (PP (IN ) (NP (NP (NN ) (NNS )) (CC ) (NP (NN ) (NNS )))) (, ) (PP (IN ) (NP (DT ) (ADJP (JJ ) (CC ) (JJ )) (NN ))))) (. )))