This function checks whether the input is a proper name, i.e., a single
(non-trivial) character.
Arguments
- x
Any object.
- error
In the case that x is not a proper name, either TRUE (default)
to throw an error or FALSE to return invisibly FALSE.
Value
If error = TRUE, either invisibly TRUE or an error is thrown.
If error = FALSE, invisibly TRUE or FALSE.
