break line after some number of measures in lilypond

I have this as a sample notation example. How would I specify to have exactly 4 measures per line, throughout the whole piece. I searched the whole documentation and did not find such a simple feature. Am I missing something?

\version "2.18.2"

% comment line

\header {
    title = "Ruska narodna pesma."
    composer = "Narodna pesma"
    subtitle = "-za gitaru-"
}

melody = {
    \key c \major
    \time 3/4

    e' f e |
    e, gis b |
    d c b |
    a c e |
}

\score {
    \relative c' <<
        \new Staff \melody
    >>
    \layout {
    }
}

Ok, I have found the answer on mailing lists.. so here it is as a future reference for those who might have it in need.. *(thanks David)

\version "2.18.2"

% comment line

\header {
    title = "Ruska narodna pesma."
    composer = "Narodna pesma"
    subtitle = "-za gitaru-"
}

melody = {
    \key c \major
    \time 3/4

    e' f e |
    e, gis b |
    d c b |
    % **EDIT** use manual breaks where you want them to appear
    a c e | \break
}

\score {
    \relative c' <<
        \new Staff \melody
    >>
    \layout {
    % **EDIT** also here, specify ragged-right property
    ragged-right = ##f
    }
}