length()
OlsonNames()
is.character()
For more details about the use of this function,
please read the article
vignette("chk-families").
Other scalar_checkers:
chk_count(),
chk_date(),
chk_date_time(),
chk_false(),
chk_flag(),
chk_lgl(),
chk_scalar(),
chk_string(),
chk_true()