code: def merge_users(merge_to, merge_from):
      
      # Determine most active user based on most recently created group
      assert(merge_to.username.endswith('umail.ucsb.edu'))
  
      # Merge groups
      for u2g in merge_from.groups_assocs[:]:
          merge_to.group_with(merge_from, u2g.project, bypass_limit=True)
  
      # merge classes and files
      merge_to.classes.extend(merge_from.classes)
      merge_to.files.extend(merge_from.files)
  
      # update file ownership
      for sub in Submission.query_by(created_by=merge_from).all():
          sub.created_by = merge_to
  
      # Delete the secondary user
      Session.delete(merge_from)
docs: Merge a non-umail account with a umail account.