汇总Golang经常使用的第三方库，比如 cobra 等
介绍
package main
import (
"fmt"
"net/http"
"os"
)
func main() {
// Open File
f, err := os.Open("/usr/local/Cellar/graphviz/10.0.1/share/doc/graphviz/libguide.pdf")
if err != nil {
panic(err)
}
defer f.Close()
buffer := make([]byte, 512)
if _, err := f.Read(buffer); err != nil {
panic(err)
}
contentType := http.DetectContentType(buffer)
fmt.Println("Content Type: " + contentType)
}