but i think here michael cohen has a credibility problem. it's like that old perry mason series that said were you lying then or are you lying now? michael cohen has a track record of giving false statements, whether that was initially to the mueller team, or perhaps he's lying now to save his own hide. >> guy lewis, how big a deal is that when you look at the shift of what we've seen with what michael cohen has been saying? >> that is a good point. because cohen does make for a challenging witness. but we've seen mueller put people on the witness stand already in the manafort case, for example, who've lied, who testified falsely to agents, to the grand jury and others. what it means, david, is that cohen and others are both going to have to corroborate each other. and also be significantly corroborated by the documents and other independent evidence. >> don, we've got a lot of balls up in the air. let me ask you about one other