validate industry NAICS codes
Examples
naics_is.valid(c(22, "022", " 22", 111, "4239", 423860))
#> Error in naics_is.valid(c(22, "022", " 22", 111, "4239", 423860)): could not find function "naics_is.valid"
# table(naics_is.valid(frs_by_naics$NAICS)) / NROW(frs_by_naics)