code: func (c *Redshift) ModifyClusterSubnetGroup(input *ModifyClusterSubnetGroupInput) (*ModifyClusterSubnetGroupOutput, error) {
  	req, out := c.ModifyClusterSubnetGroupRequest(input)
  	return out, req.Send()
  }
docs: // ModifyClusterSubnetGroup API operation for Amazon Redshift.
  //
  // Modifies a cluster subnet group to include the specified list of VPC subnets.
  // The operation replaces the existing list of subnets with the new list of
  // subnets.
  //
  // Returns awserr.Error for service API and SDK errors. Use runtime type assertions
  // with awserr.Error's Code and Message methods to get detailed information about
  // the error.
  //
  // See the AWS API reference guide for Amazon Redshift's
  // API operation ModifyClusterSubnetGroup for usage and error information.
  //
  // Returned Error Codes:
  //   * ErrCodeClusterSubnetGroupNotFoundFault "ClusterSubnetGroupNotFoundFault"
  //   The cluster subnet group name does not refer to an existing cluster subnet
  //   group.
  //
  //   * ErrCodeClusterSubnetQuotaExceededFault "ClusterSubnetQuotaExceededFault"
  //   The request would result in user exceeding the allowed number of subnets
  //   in a cluster subnet groups. For information about increasing your quota,
  //   go to Limits in Amazon Redshift (https://docs.aws.amazon.com/redshift/latest/mgmt/amazon-redshift-limits.html)
  //   in the Amazon Redshift Cluster Management Guide.
  //
  //   * ErrCodeSubnetAlreadyInUse "SubnetAlreadyInUse"
  //   A specified subnet is already in use by another cluster.
  //
  //   * ErrCodeInvalidSubnet "InvalidSubnet"
  //   The requested subnet is not valid, or not all of the subnets are in the same
  //   VPC.
  //
  //   * ErrCodeUnauthorizedOperation "UnauthorizedOperation"
  //   Your account is not authorized to perform the requested operation.
  //
  //   * ErrCodeDependentServiceRequestThrottlingFault "DependentServiceRequestThrottlingFault"
  //   The request cannot be completed because a dependent service is throttling
  //   requests made by Amazon Redshift on your behalf. Wait and retry the request.
  //
  // See also, https://docs.aws.amazon.com/goto/WebAPI/redshift-2012-12-01/ModifyClusterSubnetGroup