func (s *TasksCancelService) Header(name string, value string) *TasksCancelService {
	if s.headers == nil {
		s.headers = http.Header{}
	}
	s.headers.Add(name, value)
	return s
}
Header adds a header to the request.
package elastic
import (
	"context"
	"fmt"
	"net/http"
	"net/url"
	"strings"
	"github.com/olivere/elastic/v7/uritemplates"
)
type TasksCancelService struct {
	client *Client
	pretty     *bool        
	human      *bool        
	errorTrace *bool        
	filterPath []string     
	headers    http.Header  
	taskId       string
	actions      []string
	nodeId       []string
	parentTaskId string
}
func NewTasksCancelService(client *Client) *TasksCancelService {
	return &TasksCancelService{
		client: client,
	}
}
func (s *TasksCancelService) Pretty(pretty bool) *TasksCancelService {
	s.pretty = &pretty
	return s
}
func (s *TasksCancelService) Human(human bool) *TasksCancelService {
	s.human = &human
	return s
}
func (s *TasksCancelService) ErrorTrace(errorTrace bool) *TasksCancelService {
	s.errorTrace = &errorTrace
	return s
}
func (s *TasksCancelService) FilterPath(filterPath ...string) *TasksCancelService {
	s.filterPath = filterPath
	return s
}