proscribes turning the prosecution completely over to private counsel for interested parties, but it certainly did not proscribe all participation by such counsel. . . . The limits of such allowable assistance were also suggested: assistance may not extend to the point that “counsel for the private party [is] ... in control of the prosecution.” Id.8 We therefore read Young at least implicitly to approve (or certainly not to forbid) the practice of allowing private counsel for interested parties to participate formally with government counsel in the prosecution of contempt citations so long as that participation (1) has been approved by government counsel; (2) consists solely of rendering assistance in a subordinate role to government counsel; and (3) does not rise in practice to the level of effective control of the prosecution. As indicated, we find authority for this rule of limited participation at least implicit in Young and we think it wholly conformable to Young 's underlying principles. Accordingly, we adopt it as the appropriate rule governing the participation of private counsel for interested parties in contempt prosecutions.