This branch was made because we were having problems with rebasing the original filter-interface branch. Filter-interface was used to make interface for filters and adding into pipeline made a new file (filter.go) that conatins package Filter. This package has the filter interface, with one filter, NoOp. More filters can be added. The filtering stage was placed inbetween lexing and encoding by changing the LexTo function to have the filter as it's destination and making the destination of the filter to be r.encoders