i.e. returns
`output <- (x - mean) / (sqrt(var) + epsilon) * gamma + beta`

`k_batch_normalization(x, mean, var, beta, gamma, axis = -1, epsilon = 0.001)`

A tensor.

- x
Input tensor or variable.

- mean
Mean of batch.

- var
Variance of batch.

- beta
Tensor with which to center the input.

- gamma
Tensor by which to scale the input.

- axis
Axis (axis indexes are 1-based). Pass -1 (the default) to select the last axis.

- epsilon
Fuzz factor.

This function is part of a set of Keras backend functions that enable lower level access to the core operations of the backend tensor engine (e.g. TensorFlow, CNTK, Theano, etc.).

You can see a list of all available backend functions here: https://tensorflow.rstudio.com/reference/keras/index.html#backend.