code: def substitute_params(self, substitutions):
          
          param_dict = {}
          # TODO: this should be yaml.add_implicit_resolver()
          for k, v in self.param_dict.items():
              param_dict[k] = replace_substitutions(v, substitutions)
          return param_dict
docs: Substitute param values in our param_dict from params
  
          Args:
              substitutions (Map or dict): Values to substitute. E.g. Map of
                  {"name": "me"}
  
          E.g. if self.param_dict is:
              {"name": "$(name):pos", "exposure": 1.0}
          And substitutions is:
              {"name": "me"}
          After the call self.param_dict will be:
              {"name": "me:pos", "exposure": 1.0}