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: createpartitions.go
    path of file: ./repos/kafka-go
    
    the code of the file until where you have to start completion: package kafka

import (
	"context"
	"fmt"
	"net"
	"time"

	"github.com/segmentio/kafka-go/protocol/createpartitions"
)

// CreatePartitionsRequest represents a request sent to a kafka broker to create
// and update topic parititions.
type CreatePartitionsRequest str
    
func (c *Client) CreatePartitions(ctx context.Context, req *CreatePartitionsRequest) (*CreatePartitionsResponse, error) {
	topics := make([]createpartitions.RequestTopic, len(req.Topics))

	for i, t := range req.Topics {
		topics[i] = createpartitions.RequestTopic{
			Name:        t.Name,
			Count:       t.Count,
			Assignments: t.assignments(),
		}
	}

	m, err := c.roundTrip(ctx, req.Addr, &createpartitions.Request{
		Topics:       topics,
		TimeoutMs:    c.timeoutMs(ctx, defaultCreatePartitionsTimeout),
		ValidateOnly: req.ValidateOnly,
	})

	if err != nil {
		return nil, fmt.Errorf("kafka.(*Client).CreatePartitions: %w", err)
	}

	res := m.(*createpartitions.Response)
	ret := &CreatePartitionsResponse{
		Throttle: makeDuration(res.ThrottleTimeMs),
		Errors:   make(map[string]error, len(res.Results)),
	}

	for _, t := range res.Results {
		ret.Errors[t.Name] = makeError(t.ErrorCode, t.ErrorMessage)
	}

	return ret, nil
}