Is a object a Felt URL?

Usage

is_felt_url(x)

check_felt_url(x, allow_null = FALSE, arg = caller_arg(x), call = caller_env())

x: Object to check.
allow_null: If TRUE, check_felt_url() allows a NULL input without an error. Defaults to FALSE.
arg: An argument name as a string. This argument will be mentioned in error messages as the input that is at the origin of a problem.
call: The execution environment of a currently running function, e.g. caller_env(). The function will be mentioned in error messages as the source of the error. See the call argument of abort() for more information.