question: private static void writeJpegFile ( OutputStream os , List < Section > sections ) throws IOException { os . write ( 0xff ) ; os . write ( M_SOI ) ; for ( Section section : sections ) { os . write ( 0xff ) ; os . write ( section . marker ) ; if ( section . length > 0 ) { int lh = section . length > > 8 ; int ll = section . length & 0xff ; os . write ( lh ) ; os . write ( ll ) ; } os . write ( section . data ) ; } }
target:  Write a list of sections to a Jpeg file.