def boundary_integral(self, child, discretised_child, region):
    '\n        Implements the boundary integral for a spatial method.\n\n        Parameters\n        ----------\n        child: :class:`pybamm.Symbol`\n            The symbol to which is being integrated\n        discretised_child: :class:`pybamm.Symbol`\n            The discretised symbol of the correct size\n        region: str\n            The region of the boundary over which to integrate. If region is None\n            (default) the integration is carried out over the entire boundary. If\n            region is `negative tab` or `positive tab` then the integration is only\n            carried out over the appropriate part of the boundary corresponding to\n            the tab.\n\n        Returns\n        -------\n        :class: `pybamm.Array`\n            Contains the result of acting the discretised boundary integral on\n            the child discretised_symbol\n        '
    raise NotImplementedError
Implements the boundary integral for a spatial method.

Parameters
----------
child: :class:`pybamm.Symbol`
    The symbol to which is being integrated
discretised_child: :class:`pybamm.Symbol`
    The discretised symbol of the correct size
region: str
    The region of the boundary over which to integrate. If region is None
    (default) the integration is carried out over the entire boundary. If
    region is `negative tab` or `positive tab` then the integration is only
    carried out over the appropriate part of the boundary corresponding to
    the tab.

Returns
-------
:class: `pybamm.Array`
    Contains the result of acting the discretised boundary integral on
    the child discretised_symbol
def boundary_integral(self, child, discretised_child, region):
    '\n        Implements the boundary integral for a spatial method.\n\n        Parameters\n        ----------\n        child: :class:`pybamm.Symbol`\n            The symbol to which is being integrated\n        discretised_child: :class:`pybamm.Symbol`\n            The discretised symbol of the correct size\n        region: str\n            The region of the boundary over which to integrate. If region is None\n            (default) the integration is carried out over the entire boundary. If\n            region is `negative tab` or `positive tab` then the integration is only\n            carried out over the appropriate part of the boundary corresponding to\n            the tab.\n\n        Returns\n        -------\n        :class: `pybamm.Array`\n            Contains the result of acting the discretised boundary integral on\n            the child discretised_symbol\n        '
    raise NotImplementedError