def search_down spath
            return self if spath==path
            return nil if (spath=~/^#{path}\/(\w+)\/?/)!=0
            if iota = @iotas[$1]
                return iota if iota.path==spath    # needed as Door doesn't implement #search_down
                return iota.search_down spath
            end
            nil
        end
def search_down spath
            return self if spath==path
            return nil if (spath=~/^#{path}\/(\w+)\/?/)!=0
            if iota = @iotas[$1]
                return iota if iota.path==spath    # needed as Door doesn't implement #search_down
                return iota.search_down spath
            end
            nil
        end
search through all children for a matching Iota

 @param [String] spath the full path of the earch Iota

 @return [Iota] if found

 @see Particle#initialize used to transform @src and @dst JSON data into refrences