code: def merge_context(self, tag, metadata):
          
          self.entities.append(tag)
          for k in metadata.keys():
              if k not in self.metadata:
                  self.metadata[k] = k
docs: merge into contextManagerFrame new entity and metadata.
  
          Appends tag as new entity and adds keys in metadata to keys in
          self.metadata.
  
          Args:
              tag(str): entity to be added to self.entities
              metadata(object): metadata containes keys to be added to self.metadata