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

        # Example

        ```python
        c = cgns(...)
        Stage0 += c
        Stage1 += c.runtime()
        ```
        """
        self.rt += comment('CGNS')
        self.rt += packages(ospackages=self.__runtime_ospackages)
        self.rt += self.__bb.runtime(_from=_from)
        return str(self.rt)
Generate the set of instructions to install the runtime specific
        components from a build in a previous stage.

        # Example

        ```python
        c = cgns(...)
        Stage0 += c
        Stage1 += c.runtime()
        ```
        
hpccm/building_blocks/cgns.py