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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 byaxis_in(self):
 """Object to index ``self`` along input dimensions. Examples -------- Indexing with integers or slices: FunctionSpace(IntervalProd(0.0, 1.0)) FunctionSpace(IntervalProd(0.0, 2.0)) FunctionSpace(IntervalProd([ 0., 0.], [ 2., 3.])) Lists can be used to stack spaces arbitrarily: FunctionSpace(IntervalProd([ 0., 0., 0.], [ 3., 2., 3.])) """

        space = self

        class FspaceByaxisIn(object):

            """Helper class for indexing by input axes."""

            def __getitem__(self, indices):
                """Return ``self[indices]``.

                Parameters
                ----------
                indices : index expression
                    Object used to index the space domain.

                Returns
                -------
                space : `FunctionSpace`
                    The resulting space with same output data type, but
                    indexed domain.
                """
                domain = space.domain[indices]
                return FunctionSpace(domain, out_dtype=space.out_dtype)

            def __repr__(self):
                """Return ``repr(self)``."""
                return repr(space) + '.byaxis_in'

        return FspaceByaxisIn()