A logical value. If FALSE, NA values
cause an error; otherwise they do not. Like na.rm in many
stats package functions, except that the position of the failing
values does not change.
severity
How severe should the consequences of the assertion be?
Either "stop", "warning", "message", or "none".
Value
is_uk_postcode returns TRUE if the input string
contains a valid UK postcode. The assert_* function returns nothing but
throws an error when the is_* function returns FALSE.