func DeleteRecipient() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/recipients", host)
	request.Method = "DELETE"
	request.Body = []byte(` [
  "recipient_id1", 
  "recipient_id2"
]`)
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
DeleteRecipient : Delete Recipient
DELETE /contactdb/recipients
package main
import (
	"fmt"
	"log"
	"os"
	"github.com/sendgrid/sendgrid-go"
)
func CreateaCustomField() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/custom_fields", host)
	request.Method = "POST"
	request.Body = []byte(` {
  "name": "pet", 
  "type": "text"
}`)
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func Retrieveallcustomfields() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/custom_fields", host)
	request.Method = "GET"
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func RetrieveaCustomField() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/custom_fields/{custom_field_id}", host)
	request.Method = "GET"
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func DeleteaCustomField() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/custom_fields/{custom_field_id}", host)
	request.Method = "DELETE"
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func CreateaList() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/lists", host)
	request.Method = "POST"
	request.Body = []byte(` {
  "name": "your list name"
}`)
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func Retrievealllists() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/lists", host)
	request.Method = "GET"
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func DeleteMultiplelists() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/lists", host)
	request.Method = "DELETE"
	request.Body = []byte(` [
  1, 
  2, 
  3, 
  4
]`)
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func UpdateaList() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/lists/{list_id}", host)
	request.Method = "PATCH"
	request.Body = []byte(` {
  "name": "newlistname"
}`)
	queryParams := make(map[string]string)
	queryParams["list_id"] = "1"
	request.QueryParams = queryParams
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func Retrieveasinglelist() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/lists/{list_id}", host)
	request.Method = "GET"
	queryParams := make(map[string]string)
	queryParams["list_id"] = "1"
	request.QueryParams = queryParams
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func DeleteaList() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/lists/{list_id}", host)
	request.Method = "DELETE"
	queryParams := make(map[string]string)
	queryParams["delete_contacts"] = "true"
	request.QueryParams = queryParams
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func AddMultipleRecipientstoaList() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/lists/{list_id}/recipients", host)
	request.Method = "POST"
	request.Body = []byte(` [
  "recipient_id1", 
  "recipient_id2"
]`)
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func RetrieveallrecipientsonaList() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/lists/{list_id}/recipients", host)
	request.Method = "GET"
	queryParams := make(map[string]string)
	queryParams["page"] = "1"
	queryParams["page_size"] = "1"
	queryParams["list_id"] = "1"
	request.QueryParams = queryParams
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func AddaSingleRecipienttoaList() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/lists/{list_id}/recipients/{recipient_id}", host)
	request.Method = "POST"
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func DeleteaSingleRecipientfromaSingleList() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/lists/{list_id}/recipients/{recipient_id}", host)
	request.Method = "DELETE"
	queryParams := make(map[string]string)
	queryParams["recipient_id"] = "1"
	queryParams["list_id"] = "1"
	request.QueryParams = queryParams
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func UpdateRecipient() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/recipients", host)
	request.Method = "PATCH"
	request.Body = []byte(` [
  {
    "email": "jones@example.com", 
    "first_name": "Guy", 
    "last_name": "Jones"
  }
]`)
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func Addrecipients() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/recipients", host)
	request.Method = "POST"
	request.Body = []byte(` [
  {
    "age": 25, 
    "email": "example@example.com", 
    "first_name": "", 
    "last_name": "User"
  }, 
  {
    "age": 25, 
    "email": "example2@example.com", 
    "first_name": "Example", 
    "last_name": "User"
  }
]`)
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
func Retrieverecipients() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/recipients", host)
	request.Method = "GET"
	queryParams := make(map[string]string)
	queryParams["page"] = "1"
	queryParams["page_size"] = "1"
	request.QueryParams = queryParams
	response, err := sendgrid.API(request)
	if err != nil {
		log.Println(err)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}