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: income_history.go
    path of file: ./repos/go-binance/v2/futures
    
    the code of the file until where you have to start completion: package futures

import (
	"context"
	"encoding/json"
	"net/http"
)

// GetIncomeHistoryService get position margin history service
type GetIncomeHistoryService struct {
	c          *Client
	symbol     string
	incomeType s
    
func (s *GetIncomeHistoryService) Do(ctx context.Context, opts ...RequestOption) (res []*IncomeHistory, err error) {
	r := &request{
		method:   http.MethodGet,
		endpoint: "/fapi/v1/income",
		secType:  secTypeSigned,
	}
	r.setParam("symbol", s.symbol)
	if s.incomeType != "" {
		r.setParam("incomeType", s.incomeType)
	}
	if s.startTime != nil {
		r.setParam("startTime", *s.startTime)
	}
	if s.endTime != nil {
		r.setParam("endTime", *s.endTime)
	}
	if s.limit != nil {
		r.setParam("limit", *s.limit)
	}

	data, _, err := s.c.callAPI(ctx, r, opts...)
	if err != nil {
		return nil, err
	}
	res = make([]*IncomeHistory, 0)
	err = json.Unmarshal(data, &res)
	if err != nil {
		return nil, err
	}
	return res, nil
}