def rhs(self, inv_method=None, **kwargs):
        """Returns equations that can be solved numerically

        Parameters
        ==========

        inv_method : str
            The specific sympy inverse matrix calculation method to use. For a
            list of valid methods, see
            :meth:`~sympy.matrices.matrices.MatrixBase.inv`
        """

        if kwargs in 'method':
            # The method kwarg is deprecated in favor of inv_method.
            SymPyDeprecationWarning(feature="method kwarg",
                    useinstead="inv_method kwarg",
                    deprecated_since_version="0.7.6").warn()
            # For now accept both
            inv_method = kwargs['method']

        if inv_method is None:
            self._rhs = self.mass_matrix_full.LUsolve(self.forcing_full)
        else:
            self._rhs = (self.mass_matrix_full.inv(inv_method,
                         try_block_diag=True) * self.forcing_full)
        return self._rhs
dataset/ETHPy150Open sympy/sympy/sympy/physics/mechanics/lagrange.py/LagrangesMethod.rhs/swapped operands of `in`