Usage

    # Usage for curl
    # Get your own ip address
    curl ifcfg.cn

    # Echo your request
    curl ifcfg.cn/echo

    # or with pretty json output(indented)
    curl ifcfg.cn/echo | json_pp

    # Usage for iwr in Windows PowerShell
    # iwr is an alias of Invoke-WebRequest
    # Get your own ip address
    $resp = iwr ifcfg.cn
    $resp.Content

    # Echo your request
    $resp = iwr ifcfg.cn/echo
    $resp.Content