package importer import ( "io" ) // CountingWriter implements io.Writer. var _ io.Writer = &CountingWriter{} type CountingWriter struct { bytesWritten uint64 } func (cw *CountingWriter) Write(p []byte) (n int, err error) { cw.bytesWritten += uint64(len(p)) return len(p), nil } func (cw *CountingWriter) BytesWritten() uint64 { return cw.bytesWritten }