list.go
func (l List) From(ctx context.Context) Context {
	ctx = newContext(ctx, l)
	return &contextT{ctx: ctx}
}
func (l List) From(ctx context.Context) Context {
	ctx = newContext(ctx, l)
	return &contextT{ctx: ctx}
}
func ( l List ) From ( ctx context . Context ) Context { ctx = newContext ( ctx , l ) return & contextT { ctx : ctx } }
// From returns a new context with key/value pairs copied both from
// the list and the context.
From returns a new context with key / value pairs copied both from the list and the context .