Hi! I've recently come a cross an interesting phenomenon - the shifting of stress from a noun itself onto the preceding preposition. Examples that I've noticed, include за́ руку, до́ смерти and во́ полe. I'd really appreciate it, if someone could shed some light on this phenomenon. Is there a rule describing which nouns this phenomenon is specific to? Is the shifting of stress onto the prepositon compulsory in common speech, or is it simply a stylistic thing that people might do to make a given sentence sound better (especially in a song, so that it would rhyme)? Спасибо заранее за все ответы!