def __repr__(self):
return '<STR_LIT>' % self.__class__.__name__<EOL>
String representation of a ``Solver`` instance.

        Returns
        -------
        str
            The string representation of the current ``Solver`` instance.

        Example
        -------

        >>> from dataql.solvers.registry import Registry
        >>> registry = Registry()
        >>> from datetime import date
        >>> registry.register(date, allow_class=True)
        >>> class MySolver(Solver):
        ...     def solve(self, value, filter): return value
        >>> MySolver(registry)
        <MySolver>