Returns either the last expiration date before Date, or the
first expiration date after Date (if expired==FALSE).
# S3 method for instrument
expires(x, Date, expired = TRUE, silent = FALSE, ...)Can be a Date or character string. When expires is a
vector, the retuned value will be one of the two values of expires
that are closest to Date. (which one will be determined by the value
of expired)
TRUE/FALSE. This determines which date will be used when
expires is a vector. If expired is TRUE the date
returned will be the last one before Date. If expired is
FALSE the first one after Date will be returned. Note that
if expires is a single value, expired will be ignored.
silence warnings?