Determine if x consists out of site_models objects
See also
Use create_site_model to create a site model
Examples
check_empty_beautier_folder()
jc69_site_model <- create_jc69_site_model()
gtr_site_model <- create_gtr_site_model()
both_site_models <- list(jc69_site_model, gtr_site_model)
# TRUE
are_site_models(jc69_site_model)
#> [1] TRUE
# TRUE
are_site_models(gtr_site_model)
#> [1] TRUE
# TRUE
are_site_models(both_site_models)
#> [1] TRUE
check_empty_beautier_folder()