io: improve signature of each-block and each-line.
io: improve signature of each-block and each-line.

erg/factor,mcandre/factor,mcandre/factor,mcandre/factor,erg/factor,mcandre/factor,mcandre/factor,erg/factor,erg/factor,mcandre/factor,erg/factor,mcandre/factor,erg/factor,erg/factor