tweak handling of NULL/NIL printing.
tweak handling of NULL/NIL printing.

tim777z/opencog,andre-senna/opencog,sanuj/opencog,anitzkin/opencog,printedheart/atomspace,ruiting/opencog,inflector/atomspace,ceefour/atomspace,kinoc/opencog,kinoc/opencog,rodsol/opencog,ArvinPan/opencog,TheNameIsNigel/opencog,ArvinPan/opencog,prateeksaxena2809/opencog,yantrabuddhi/opencog,rodsol/atomspace,kinoc/opencog,misgeatgit/atomspace,ceefour/atomspace,virneo/atomspace,williampma/opencog,printedheart/opencog,AmeBel/opencog,eddiemonroe/opencog,ruiting/opencog,ruiting/opencog,ruiting/opencog,sumitsourabh/opencog,iAMr00t/opencog,Selameab/opencog,virneo/opencog,AmeBel/opencog,ceefour/atomspace,cosmoharrigan/atomspace,roselleebarle04/opencog,inflector/opencog,iAMr00t/opencog,sanuj/opencog,prateeksaxena2809/opencog,rohit12/opencog,jlegendary/opencog,rodsol/atomspace,rohit12/opencog,rohit12/opencog,virneo/atomspace,gaapt/opencog,virneo/opencog,Selameab/atomspace,ArvinPan/opencog,ArvinPan/opencog,virneo/opencog,misgeatgit/opencog,iAMr00t/opencog,cosmoharrigan/opencog,eddiemonroe/opencog,yantrabuddhi/opencog,Allend575/opencog,ceefour/opencog,Selameab/atomspace,yantrabuddhi/atomspace,yantrabuddhi/opencog,Allend575/opencog,ArvinPan/atomspace,zhaozengguang/opencog,ArvinPan/atomspace,Selameab/opencog,eddiemonroe/opencog,williampma/opencog,MarcosPividori/atomspace,gaapt/opencog,williampma/opencog,misgeatgit/opencog,kinoc/opencog,AmeBel/opencog,jlegendary/opencog,eddiemonroe/atomspace,AmeBel/atomspace,cosmoharrigan/opencog,zhaozengguang/opencog,ceefour/opencog,anitzkin/opencog,williampma/opencog,anitzkin/opencog,roselleebarle04/opencog,eddiemonroe/atomspace,AmeBel/opencog,AmeBel/opencog,prateeksaxena2809/opencog,jswiergo/atomspace,ruiting/opencog,roselleebarle04/opencog,gaapt/opencog,rodsol/opencog,Tiggels/opencog,gavrieltal/opencog,inflector/opencog,rTreutlein/atomspace,ceefour/opencog,rTreutlein/atomspace,iAMr00t/opencog,printedheart/opencog,williampma/atomspace,inflector/opencog,Selameab/opencog,shujingke/opencog,prateeksaxena2809/opencog,Allend575/opencog,sumitsourabh/opencog,jswiergo/atomspace,cosmoharrigan/opencog,yantrabuddhi/opencog,misgeatgit/atomspace,iAMr00t/opencog,printedheart/opencog,yantrabuddhi/opencog,inflector/opencog,andre-senna/opencog,kim135797531/opencog,UIKit0/atomspace,inflector/atomspace,Selameab/atomspace,sanuj/opencog,rTreutlein/atomspace,anitzkin/opencog,rodsol/opencog,ceefour/opencog,eddiemonroe/atomspace,gaapt/opencog,inflector/atomspace,TheNameIsNigel/opencog,rodsol/opencog,printedheart/atomspace,andre-senna/opencog,printedheart/opencog,andre-senna/opencog,zhaozengguang/opencog,shujingke/opencog,iAMr00t/opencog,jlegendary/opencog,rohit12/atomspace,TheNameIsNigel/opencog,ceefour/opencog,gavrieltal/opencog,misgeatgit/atomspace,misgeatgit/opencog,printedheart/atomspace,AmeBel/opencog,ceefour/atomspace,yantrabuddhi/atomspace,anitzkin/opencog,UIKit0/atomspace,roselleebarle04/opencog,tim777z/opencog,prateeksaxena2809/opencog,misgeatgit/opencog,Selameab/opencog,misgeatgit/atomspace,misgeatgit/opencog,yantrabuddhi/atomspace,ArvinPan/opencog,Tiggels/opencog,printedheart/opencog,Selameab/opencog,virneo/atomspace,jswiergo/atomspace,cosmoharrigan/atomspace,rohit12/opencog,williampma/opencog,gavrieltal/opencog,rohit12/atomspace,AmeBel/opencog,inflector/atomspace,TheNameIsNigel/opencog,kim135797531/opencog,rodsol/opencog,ArvinPan/atomspace,gaapt/opencog,eddiemonroe/opencog,sanuj/opencog,jlegendary/opencog,UIKit0/atomspace,printedheart/atomspace,kinoc/opencog,ceefour/opencog,ceefour/opencog,kim135797531/opencog,AmeBel/atomspace,Tiggels/opencog,printedheart/opencog,eddiemonroe/atomspace,cosmoharrigan/atomspace,kim135797531/opencog,gavrieltal/opencog,ruiting/opencog,williampma/opencog,Tiggels/opencog,rTreutlein/atomspace,Tiggels/opencog,Selameab/atomspace,gavrieltal/opencog,Allend575/opencog,Tiggels/opencog,andre-senna/opencog,cosmoharrigan/atomspace,yantrabuddhi/atomspace,virneo/opencog,inflector/opencog,virneo/opencog,shujingke/opencog,TheNameIsNigel/opencog,anitzkin/opencog,misgeatgit/opencog,ruiting/opencog,andre-senna/opencog,tim777z/opencog,virneo/opencog,sumitsourabh/opencog,jlegendary/opencog,virneo/atomspace,roselleebarle04/opencog,misgeatgit/opencog,kinoc/opencog,rTreutlein/atomspace,sumitsourabh/opencog,UIKit0/atomspace,inflector/opencog,tim777z/opencog,Allend575/opencog,williampma/atomspace,gavrieltal/opencog,zhaozengguang/opencog,Selameab/opencog,zhaozengguang/opencog,eddiemonroe/opencog,MarcosPividori/atomspace,jlegendary/opencog,sumitsourabh/opencog,tim777z/opencog,rohit12/atomspace,MarcosPividori/atomspace,yantrabuddhi/opencog,ArvinPan/opencog,zhaozengguang/opencog,yantrabuddhi/atomspace,tim777z/opencog,misgeatgit/opencog,rodsol/atomspace,MarcosPividori/atomspace,Allend575/opencog,ArvinPan/atomspace,cosmoharrigan/opencog,AmeBel/atomspace,shujingke/opencog,shujingke/opencog,eddiemonroe/atomspace,sumitsourabh/opencog,andre-senna/opencog,gaapt/opencog,shujingke/opencog,rohit12/opencog,sanuj/opencog,prateeksaxena2809/opencog,rodsol/opencog,AmeBel/atomspace,cosmoharrigan/opencog,williampma/atomspace,virneo/opencog,kim135797531/opencog,kim135797531/opencog,rohit12/opencog,roselleebarle04/opencog,inflector/opencog,kim135797531/opencog,prateeksaxena2809/opencog,eddiemonroe/opencog,yantrabuddhi/opencog,inflector/atomspace,shujingke/opencog,rodsol/atomspace,cosmoharrigan/opencog,misgeatgit/opencog,misgeatgit/atomspace,sumitsourabh/opencog,jlegendary/opencog,AmeBel/atomspace,Allend575/opencog,williampma/atomspace,rohit12/atomspace,gaapt/opencog,roselleebarle04/opencog,gavrieltal/opencog,TheNameIsNigel/opencog,jswiergo/atomspace,eddiemonroe/opencog,kinoc/opencog,sanuj/opencog,inflector/opencog,anitzkin/opencog