// QuantityFlag is a helper that makes a quantity flag (using standard flag package).
// Will panic if defaultValue is not a valid quantity.
func QuantityFlag(flagName, defaultValue, description string) *Quantity {
q := MustParse(defaultValue)
flag.Var(NewQuantityFlagValue(&q), flagName, description)
return &q
}
func init() {
// Tie the command-line flag to the intervalFlag variable and
// set a usage message.
flag.Var(&intervalFlag, "deltaT", "comma-separated list of intervals to use between events")
}