To check for empty string after a portion of the string in python 3.6

[srinivasan]

Dear Python Experts,

Could you please help me, as am still learning python syntax, how can
I add conditional check for empty string after running "hcitool scan"
(ie., when there is no Bluetooth devices discovered) ie., after the
word  "Scanning..." , when there are no Bluetooth discover-able
devices and then return False in the below python code snippet?


Command:
~$ sudo hcitool scan
Scanning ...                              -------------------------->
When there are no BT devices
~$ sudo hcitool scan
Scanning ...
64:A2:F9:06:63:79 OnePlus 6 ---------------------------> When there
are BT devices
~$

Python code snippet:
    def bluetooth_scan(self):
        """
            Start bluetooth scanning process.

            :return: Return device info by mac address and name.
        """
        cmd = "sudo hciconfig hci0 up"
        self._helper.execute_cmd_return_code(cmd)

        cmd = "sudo hcitool scan"
        res = self._helper.execute_cmd_output_string(cmd)

        return res

Many Thanks in advance,