code: def set_param(self, params, value=None):
          
          if isinstance(params, Mapping):
              params = params.items()
          elif isinstance(params, STRING_TYPES) and value is not None:
              params = [(params, value)]
          for key, val in params:
              _check_call(_LIB.XGBoosterSetParam(self.handle, c_str(key), c_str(str(val))))
docs: Set parameters into the Booster.
  
          Parameters
          ----------
          params: dict/list/str
             list of key,value pairs, dict of key to value or simply str key
          value: optional
             value of the specified parameter, when params is str key