Get first or all references of an R object
Assert that there are no references among the identified globals
find_references(x, first_only = FALSE)assert_no_references(x, action = c("error", "warning", "message", "string"))
The R object to be checked.
If TRUE, only the first reference is returned,
otherwise all references.
Type of action to take if a reference is found.
find_references() returns a list of one or more references
identified.
If a reference is detected, an informative error, warning, message,
or a character string is produced, otherwise NULL is returned
invisibly.