def runtime(self, _from='0'):
        """Generate the set of instructions to install the runtime specific
        components from a build in a previous stage.

        The entire `/scif` directory is copied into the runtime stage
        on the first call.  Subsequent calls do nothing.

        # Examples
        ```python
        s = scif(...)
        Stage0 += s
        Stage1 += s.runtime()
        ```

        """

        if not scif.__runtime_called:
            scif.__runtime_called = True
            return str(copy(_from=_from, src='/scif', dest='/scif'))
        else:
            return ''
Generate the set of instructions to install the runtime specific
        components from a build in a previous stage.

        The entire `/scif` directory is copied into the runtime stage
        on the first call.  Subsequent calls do nothing.

        # Examples
        ```python
        s = scif(...)
        Stage0 += s
        Stage1 += s.runtime()
        ```

        
hpccm/building_blocks/scif.py