Reshape tensors to contain only one batch dimension.

For each tensor, it checks the number of extra dimensions beyond those in the spec, and reshapes tensor to have only one batch dimension. NOTE: Each tensor's batch dimensions must be the same.

tensors Nested list/tuple or dict of batched Tensors or SparseTensors.
specs Nested list/tuple or dict of TensorSpecs, describing the shape of the non-batched Tensors.

A nested version of each tensor with a single batch dimension. A list of the batch dimensions which were flattened.

ValueError if the tensors and specs have incompatible dimensions or shapes.