Is object x a gamma site model?
Examples
check_empty_beautier_folder()
# TRUE
is_gamma_site_model(create_gamma_site_model())
#> [1] TRUE
# FALSE
is_gamma_site_model("nonsense")
#> [1] FALSE
is_gamma_site_model(NA)
#> [1] FALSE
is_gamma_site_model(NULL)
#> [1] FALSE
is_gamma_site_model("")
#> [1] FALSE
is_gamma_site_model(c())
#> [1] FALSE
check_empty_beautier_folder()