Creates a random input/target list once and repeatedly returns list.
Examples
if (FALSE) { # reticulate::py_module_available("tensorflow")
model <- create_model_lstm_cnn(
maxlen = 10,
layer_lstm = c(4),
layer_dense = c(5))
gen <- generator_dummy(model, 12)
z <- gen()
x <- z[[1]]
y <- z[[2]]
dim(x)
dim(y)
}