You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: reactions.go
    path of file: ./repos/slack
    
    the code of the file until where you have to start completion: package slack

import (
	"context"
	"net/url"
	"strconv"
)

// ItemReaction is the reactions that have happened on an item.
type ItemReaction struct {
	Name  string   `json:"name"`
	Count int      `json:"count"`
	Users []string `json:"users"`
}

// ReactedItem is an item that was reacted to, and the details of the
// reactions.
type ReactedItem struct {
	Item
	Reactions []ItemReaction
}

// GetReactionsParameters is the inputs to get reactions to an item
    
func (api *Client) AddReactionContext(ctx context.Context, name string, item ItemRef) error {
	values := url.Values{
		"token": {api.token},
	}
	if name != "" {
		values.Set("name", name)
	}
	if item.Channel != "" {
		values.Set("channel", item.Channel)
	}
	if item.Timestamp != "" {
		values.Set("timestamp", item.Timestamp)
	}
	if item.File != "" {
		values.Set("file", item.File)
	}
	if item.Comment != "" {
		values.Set("file_comment", item.Comment)
	}

	response := &SlackResponse{}
	if err := api.postMethod(ctx, "reactions.add", values, response); err != nil {
		return err
	}

	return response.Err()
}