def perform_exe_expansion(self):
        """
        This function will look through the executables section of the
        ConfigParser object and replace any values using macros with full paths.

        For any values that look like

        ${which:lalapps_tmpltbank}

        will be replaced with the equivalent of which(lalapps_tmpltbank)

        Otherwise values will be unchanged.
        """
        # Only works on executables section
        if self.has_section('executables'):
            for option, value in self.items('executables'):
                # Check the value
                newStr = self.interpolate_exe(value)
                if newStr != value:
                    self.set('executables', option, newStr)