def binary_reduce(reducer, binary_op, graph, lhs, rhs, lhs_data, rhs_data,
    out_size, lhs_map, rhs_map, out_map):
    """Perform binary operation between given data and reduce based on graph
    structure.

    Parameters
    ----------
    reducer : str
        Type of reduction: 'sum', 'max', 'min', 'mean', 'prod', 'none' (no
        reduction)
    binary_op : str
        Binary operation to perform, can be 'add', 'mul', 'sub', 'div'
    graph : GraphIndex
        The graph
    lhs : int
        The lhs target (src, dst, edge)
    rhs : int
        The rhs target (src, dst, edge)
    lhs_data : Tensor
        The lhs data
    rhs_data : Tensor
        The rhs data
    out_size : int
        Size of first dimension of output data
    lhs_map : tuple
        Two lhs id mapping arrays, one for forward pass, the other for backward
    rhs_map : tuple
        Two rhs id mapping arrays, one for forward pass, the other for backward
    out_map : tuple
        Two out id mapping arrays, one for forward pass, the other for backward

    Returns
    -------
    Tensor
        The result.
    """
    pass
