Conditional imports for serial-based interfaces

RNS/Interfaces/AX25KISSInterface.py

@@ -47,6 +47,7 @@ class AX25KISSInterface(Interface):
     serial   = None
 
     def __init__(self, owner, name, callsign, ssid, port, speed, databits, parity, stopbits, preamble, txtail, persistence, slottime, flow_control):
+        import importlib
         if importlib.util.find_spec('serial') != None:
             import serial
         else:

RNS/Interfaces/KISSInterface.py

@@ -39,6 +39,7 @@ class KISSInterface(Interface):
     serial   = None
 
     def __init__(self, owner, name, port, speed, databits, parity, stopbits, preamble, txtail, persistence, slottime, flow_control, beacon_interval, beacon_data):
+        import importlib
         if importlib.util.find_spec('serial') != None:
             import serial
         else:

RNS/Interfaces/RNodeInterface.py

@@ -71,6 +71,7 @@ class RNodeInterface(Interface):
     CALLSIGN_MAX_LEN    = 32
 
     def __init__(self, owner, name, port, frequency = None, bandwidth = None, txpower = None, sf = None, cr = None, flow_control = False, id_interval = None, id_callsign = None):
+        import importlib
         if importlib.util.find_spec('serial') != None:
             import serial
         else:

RNS/Interfaces/SerialInterface.py

@@ -30,6 +30,7 @@ class SerialInterface(Interface):
     serial   = None
 
     def __init__(self, owner, name, port, speed, databits, parity, stopbits):
+        import importlib
         if importlib.util.find_spec('serial') != None:
             import serial
         else: