Absolute path of the HIST file. Empty string if file is not present.

def hist_path(self):
        """Absolute path of the HIST file. Empty string if file is not present."""
        # Lazy property to avoid multiple calls to has_abiext.
        try:
            return self._hist_path
        except AttributeError:
            path = self.outdir.has_abiext("HIST")
            if path: self._hist_path = path
            return path