check that the index is built before allowing Gets
no reason to pass around a (usually empty) map by reference
make SequenceFile.Version an int
add some basic tests
don't pass around 'indexEntry's by reference
don't pass around indexers by reference, either
use CapitalCase for constants
start at iota + 1
improve comment
There's a fmt.Errorf, apparently
improve error handling in sequencefile.go and elsewhere