This function gets the name of all the variables in the passed file, list or
libbi
object
Examples
example_output_file <- system.file(package = "rbi", "example_output.nc")
bi_contents(example_output_file)
#> [1] "time" "alpha" "P" "Z"
#> [5] "mu" "sigma" "clock" "loglikelihood"
#> [9] "logprior"