function [out, succ] = hash_insert(hash, key)
 indx = myhash(key, hash.size);
 succ = false;
 sindx = find(hash.keys{indx}==key);
 if isempty(sindx)
     hash.keys{indx} = [key, hash.keys{indx}];
     succ = true;
 end;
 out = hash;