docs: def getUserContact(master, contact_types, uid):
      """
      This is a simple getter function that returns a user attribute
      that matches the contact_types argument, or returns None if no
      uid/match is found.
  
      @param master: BuildMaster used to query the database
      @type master: BuildMaster instance
  
      @param contact_types: list of contact attributes to look for in
                           in a given user, such as 'email' or 'nick'
      @type contact_types: list of strings
  
      @param uid: user that is searched for the contact_types match
      @type uid: integer
  
      @returns: string of contact information or None via deferred
      """
      d = master.db.users.getUser(uid)
      d.addCallback(_extractContact, contact_types, uid)
      return d