Why we call `b = b[n:]`, it may have no effect.

[wathenjiang]

Please see it in this reference: https://github.com/tidwall/bfile/blob/master/bfile.go#L212

[tidwall]

The b = b[n:] progresses the b slice forward, which is needed for the loop to terminate at for len(b) > 0 at https://github.com/tidwall/bfile/blob/master/bfile.go#L199

[wathenjiang]

@tidwall I left out the for loop, thanks you a lot.