function * Format() {
	var g, b;
	fini: while ( true ) {
		for ( g = 0; g < 5; g += 1 ) {					// groups of 5 blocks
			for ( b = 0; b < 4; b += 1 ) {				// blocks of 4 characters
				while ( true ) {
					ch = (yield)						// receive from send
					if ( ch == '\0' ) break fini;
					if ( '\n' != ch ) break
				}
				process.stdout.write( ch )				// receive from send
			}
			process.stdout.write( '  ' )				// block separator
		}
		process.stdout.write( '\n' )					// group separator
	}
	if ( g != 0 || b != 0 ) process.stdout.write( '\n' )
}

var input = "abcdefghijklmnop\nqrstuvwx\nyzxxxxxxxxxxxxx"

fmt = Format()
fmt.next()												// prime generator
for ( var i = 0; i < input.length; i += 1 ) {
	fmt.next( input[i] );								// send to yield
}
fmt.next( '\0' );										// EOF

// Local Variables: //
// comment-column: 56 //
// tab-width: 4 //
// compile-command: "node Format.js" //
// End: //