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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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