Load the model from a file.

        Parameters
        ----------
        fname : string or a memory buffer
            Input file name or memory buffer(see also save_raw)

def load_model(self, fname):
        """
        Load the model from a file.

        Parameters
        ----------
        fname : string or a memory buffer
            Input file name or memory buffer(see also save_raw)
        """
        if isinstance(fname, STRING_TYPES):  # assume file name
            if os.path.exists(fname):
                _LIB.XGBoosterLoadModel(self.handle, c_str(fname))
            else:
                raise ValueError("No such file: {0}".format(fname))
        else:
            buf = fname
            length = ctypes.c_ulong(len(buf))
            ptr = (ctypes.c_char * len(buf)).from_buffer(buf)
            _check_call(_LIB.XGBoosterLoadModelFromBuffer(self.handle, ptr, length))