
1. modified the get_sample_size_and_distance function to get the optional parameter according to the center instance
2. add one test case to test the sample_from_neighborhood by passing an random instance as exemplar

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