def _f90str(self, value):
        """Return a Fortran 90 representation of a string."""
        # Replace Python quote escape sequence with Fortran
        result = repr(str(value)).replace("\\'", "''").replace('\\"', '""')

        # Un-escape the Python backslash escape sequence
        result = result.replace('\\\\', '\\')

        return result
Return a Fortran 90 representation of a string.