code: def add(self, term, field, metadata):
          
          if term not in self.metadata:
              self.metadata[term] = {field: metadata}
              return
  
          if field not in self.metadata[term]:
              self.metadata[term][field] = metadata
              return
  
          for key in metadata.keys():
              if key in self.metadata[term][field]:
                  self.metadata[term][field][key].extend(metadata[key])
              else:
                  self.metadata[term][field][key] = metadata[key]
docs: Add metadata for a term/field pair to this instance of match data