let's go to john mcardle. hn: a lot of talk last night about former president barack obama, including in the second-most tweeted about moment, the exchange between julian castro and former vice president joe biden, a recap of what they said for our viewers. of biden, he said wants to take credit for obama's work but not answering any questions and then joe biden saying he stands with barack obama, all eight years. the former president came up so listed asck obama was one of the winners. the story noting the amount of times barack obama came up was much more than previous debates, candidates from every wing of the democratic party went out of their way to praise obama's record. it was not over whether obama's record was good, rather the argument was over who could build on the 44th president's accomplishments. this was in line with what actual democratic voters think the story notes. joe biden not backing away from barack obama last night, embracing him even more so in an instagram advertisement he put out yeste