docs: def tags_all(self):
          """List of the tags and md5s for all samples
          Args:
              None
  
          Returns:
              List of the tags and md5s for all samples
          """
          if 'tags' not in self.database.collection_names():
              print 'Warning: Searching on non-existance tags collection'
              return None
  
          cursor = self.database['tags'].find({}, {'_id':0, 'md5':1, 'tags':1})
          return [item for item in cursor]