L2SS-627: Linting: xix B008 Do not perform function calls in argument defaults.

tangostationcontrol/tangostationcontrol/devices/sdp/statistics_collector.py

@@ -236,12 +236,15 @@ class XSTCollector(StatisticsCollector):
         self.parameters["xst_subbands"][subband_slot]                = numpy.uint16(fields.subband_index)
         self.parameters["xst_integration_intervals"][subband_slot]   = fields.integration_interval()
 
-    def xst_values(self, subband_indices=range(MAX_PARALLEL_SUBBANDS)):
+    def xst_values(self, subband_indices = None):
         """ xst_blocks, but as a matrix[len(subband_indices)][MAX_INPUTS][MAX_INPUTS] of complex values.
         
             The subband indices must be in [0..MAX_PARALLEL_SUBBANDS). By default, all recorded XSTs are returned.
         """
 
+        if subband_indices is None:
+            subband_indices = range(MAX_PARALLEL_SUBBANDS)
+
         matrix = numpy.zeros((len(subband_indices), self.MAX_INPUTS, self.MAX_INPUTS), dtype=numpy.complex64)
         xst_blocks = self.parameters["xst_blocks"]
         xst_conjugated = self.parameters["xst_conjugated"]