func ForceWebsocketTransport() CallOption {
	return beforeCall(func(c *callInfo) error {
		c.forceWebsockets = true
		return nil
	})
}
ForceWebsocketTransport forces this call to use the Websocket transport.
package grpcweb
import "google.golang.org/grpc/metadata"
type callInfo struct {
	headers         metadata.MD
	trailers        metadata.MD
	forceWebsockets bool
}
type CallOption interface {
	before(*callInfo) error
	after(*callInfo)
}
type beforeCall func(c *callInfo) error
func (o beforeCall) before(c *callInfo) error { return o(c) }
func (o beforeCall) after(c *callInfo)        {}
type afterCall func(c *callInfo)
func (o afterCall) before(c *callInfo) error { return nil }
func (o afterCall) after(c *callInfo)        { o(c) }
func Header(headers *metadata.MD) CallOption {
	return afterCall(func(c *callInfo) {
		*headers = c.headers
	})
}
func Trailer(trailers *metadata.MD) CallOption {
	return afterCall(func(c *callInfo) {
		*trailers = c.trailers
	})
}