func WithIPv4Mask(mask net.IPMask) Option {
	return func(o *Options) {
		o.IPv4Mask = mask
	}
}
WithIPv4Mask will configure the limiter to use given mask for IPv4 address.
package limiter
import (
	"net"
)
type Option func(*Options)
type Options struct {
	IPv4Mask net.IPMask
	IPv6Mask net.IPMask
	TrustForwardHeader bool
}