func WithTraceHeaderName(name string) Option {
	return func(o *options) {
		o.traceHeaderName = name
	}
}
WithTraceHeaderName customizes the trace header name where trace metadata passed with requests.
Default one is `uber-trace-id`
package grpc_opentracing
import (
	"context"
	"github.com/opentracing/opentracing-go"
)
var (
	defaultOptions = &options{
		filterOutFunc: nil,
		tracer:        nil,
	}
)
type FilterFunc func(ctx context.Context, fullMethodName string) bool
type UnaryRequestHandlerFunc func(span opentracing.Span, req interface{})
type OpNameFunc func(method string) string
type options struct {
	filterOutFunc           FilterFunc
	tracer                  opentracing.Tracer
	traceHeaderName         string
	unaryRequestHandlerFunc UnaryRequestHandlerFunc
	opNameFunc              OpNameFunc
}
func evaluateOptions(opts []Option) *options {
	optCopy := &options{}
	*optCopy = *defaultOptions
	for _, o := range opts {
		o(optCopy)
	}
	if optCopy.tracer == nil {
		optCopy.tracer = opentracing.GlobalTracer()
	}
	if optCopy.traceHeaderName == "" {
		optCopy.traceHeaderName = "uber-trace-id"
	}
	return optCopy
}
type Option func(*options)
func WithFilterFunc(f FilterFunc) Option {
	return func(o *options) {
		o.filterOutFunc = f
	}
}