code: static String getTangoHost() throws DevFailed
  	{
  		//	Check if already done
  		if (tango_host==null)
  			if ((tango_host=System.getProperty("TANGO_HOST"))==null)	//	From JVM property
  				if ((tango_host=System.getenv("TANGO_HOST"))==null)		//	From Environment property
  					if ((tango_host=getFromEnvFile("TANGO_HOST"))==null)		//	From Environment file
  						Except.throw_connection_failed("TangoApi_TANGO_HOST_NOT_SET",
  									"Property \"TANGO_HOST\" not exported",
  									"TangoEnv.getTangoHost()");
  		//	else
  		return tango_host;
  	}
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