<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def validate_openssl():
 """ Validates OpenSSL to ensure it has TLS_FALLBACK_SCSV supported """

    try:
        open_ssl_exe = which("openssl")
        if not open_ssl_exe:
            raise Exception("No openssl exe found in path")

        try:
            # execute a an invalid command to get output with available options
            # since openssl does not have a --help option unfortunately
            execute_command([open_ssl_exe, "s_client", "invalidDummyCommand"])
        except subprocess.CalledProcessError as e:
            if "fallback_scsv" not in e.output:
                raise Exception("openssl does not support TLS_FALLBACK_SCSV")
    except Exception as e:
        raise MongoctlException("Unsupported OpenSSL. %s" % e)