/// Computes the mean of elements across dimensions of a tensor.
/// Reduces `input` along the dimensions given in `axis`. Unless
/// `keep_dims` is true, the rank of the tensor is reduced by 1 for each entry in
/// `axis`. If `keep_dims` is true, the reduced dimensions are retained with length 1.
/// Reduces `input` along the dimensions given in `axis`. Unless
/// `keep_dims` is true, the rank of the tensor is reduced by 1 for each entry in
/// `axis`. If `keep_dims` is true, the reduced dimensions are retained with length 1.
/// </summary>
/// <param name="input">A `Tensor`. Must be one of the following types: