code: func (g *Cloud) SetSecurityPolicyForAlphaGlobalBackendService(backendServiceName string, securityPolicyReference *computealpha.SecurityPolicyReference) error {
  	ctx, cancel := cloud.ContextWithCallTimeout()
  	defer cancel()
  
  	mc := newBackendServiceMetricContextWithVersion("set_security_policy", "", computeAlphaVersion)
  	return mc.Observe(g.c.AlphaBackendServices().SetSecurityPolicy(ctx, meta.GlobalKey(backendServiceName), securityPolicyReference))
  }
docs: // SetSecurityPolicyForAlphaGlobalBackendService sets the given
  // SecurityPolicyReference for the BackendService identified by the given name.