Writing Clients in Go: Redundancy and the `*iface` Package

bing.go

package bing

func (c *Client) DriveTime(ctx context.Context, locations ...Location) (float64, error) {
    // Call external API.
    driveTime, err := c.httpclient.Post(ctx, c.config.Endpoint+"/routing/time", ...)
    ...
    return driveTime, nil
}