LineStream.js
function emitLine(line, isEnd) {
  if (this.filters.every(function(fn) { return fn(line) }))
    emit.call(this, 'data', line, !!isEnd);
}
function emitLine(line, isEnd) {
  if (this.filters.every(function(fn) { return fn(line) }))
    emit.call(this, 'data', line, !!isEnd);
}
function emitLine ( line , isEnd ) { if ( this . filters . every ( function ( fn ) { return fn ( line ) } ) ) emit . call ( this , 'data' , line , ! ! isEnd ) ; }
emit data event if the given line is valid.

(private method)
emit data event if the given line is valid .