docs: def make_line(self,
                    response=None,
                    importance=None,
                    base=None,
                    tag=None,
                    features=None,
                    namespaces=None,
                    ):
          """Makes and returns an example string in VW syntax.
          If given, 'response', 'importance', 'base', and 'tag' are used
          to label the example.  Features for the example come from
          any given features or namespaces, as well as any previously
          added namespaces (using them up in the process).
          """
          if namespaces is not None:
              self.add_namespaces(namespaces)
          if features is not None:
              namespace = Namespace(features=features)
              self.add_namespace(namespace)
          substrings = []
          tokens = []
          if response is not None:
              token = str(response)
              tokens.append(token)
              if importance is not None:  # Check only if response is given
                  token = str(importance)
                  tokens.append(token)
                  if base is not None:  # Check only if importance is given
                      token = str(base)
                      tokens.append(token)
          if tag is not None: 
              token = "'" + str(tag)  # Tags are unambiguous if given a ' prefix
              tokens.append(token)
          else:
              token = ""  # Spacing element to avoid ambiguity in parsing
              tokens.append(token)
          substring = ' '.join(tokens)
          substrings.append(substring)
          if self.namespaces:
              for namespace in self.namespaces:
                  substring = namespace.to_string()
                  substrings.append(substring)
          else:
              substrings.append('')  # For correct syntax
          line = '|'.join(substrings)
          self._line = line
          self.namespaces = []  # Reset namespaces after their use
          return line