# Specify an action to detect a "code" parameter in the query.
req_has_query("code")
# Specify an action to detect the *lack* of a "code" parameter in the query.
req_has_query("code", negate = TRUE)
# Specify an action to detect a "language" parameter, with values containing
# "en" or "es".
req_has_query("language", "en|es")
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