The method simulate launches LibBi to simulate a model by
passing `target="joint"` to LibBi
If x is given as a 'bi_model', a libbi object will be
created from the model
# S3 method for libbi
simulate(x, ...)# S3 method for bi_model
simulate(x, ...)
an updated bi_model object
a libbi or bi_model object, or the name
of a file containing the model
options to be passed to run.libbi