diff --git a/pySim/esim/saip/batch.py b/pySim/esim/saip/batch.py
index 2af05790..9fad44fe 100644
--- a/pySim/esim/saip/batch.py
+++ b/pySim/esim/saip/batch.py
@@ -62,7 +62,7 @@ class BatchPersonalization:
     def __init__(self,
                  n: int,
                  src_pes: ProfileElementSequence,
-                 params: list[ParamAndSrc]=None,
+                 params: list[ParamAndSrc]=[],
                  csv_rows: Generator=None,
                 ):
         """
@@ -71,10 +71,10 @@ class BatchPersonalization:
                  copied.
         params: list of ParamAndSrc instances, defining a ConfigurableParameter and corresponding ParamSource to fill in
                 profile values.
-        csv_rows: A list or generator producing all CSV rows one at a time, starting with a row containing the column
-                  headers. This is compatible with the python csv.reader. Each row gets passed to
-                  ParamSource.get_next(), such that ParamSource implementations can access the row items.
-                  See param_source.CsvSource.
+        csv_rows: A generator (or iter(list_of_rows)) producing all CSV rows one at a time, starting with a row
+                  containing the column headers. This is compatible with the python csv.reader. Each row gets passed to
+                  ParamSource.get_next(), such that ParamSource implementations can access the row items. See
+                  param_source.CsvSource.
         """
         self.n = n
         self.params = params or []
diff --git a/pySim/esim/saip/param_source.py b/pySim/esim/saip/param_source.py
index 77f2e1cc..bbd0ccce 100644
--- a/pySim/esim/saip/param_source.py
+++ b/pySim/esim/saip/param_source.py
@@ -34,6 +34,11 @@ class ParamSource:
     # This name should be short but descriptive, useful for a user interface, like 'random decimal digits'.
     name = "none"
 
+    def __init__(self, input_val:str):
+        """Subclasses must implement a constructor with this signature. The input_val is typically a user entered string
+        value, and the subclass chooses how to store it; for example ConstantSource() just does self.val = input_val."""
+        pass
+
     @classmethod
     def from_str(cls, s:str):
         """Subclasses implement this:
@@ -48,13 +53,12 @@ class ParamSource:
            This default implementation is an empty source."""
         raise ParamSourceExhaustedExn()
 
-
 class ConstantSource(ParamSource):
     """one value for all"""
     name = "constant"
 
-    def __init__(self, val:str):
-        self.val = val
+    def __init__(self, input_val:str):
+        self.val = input_val
 
     def get_next(self, csv_row:dict=None):
         return self.val
@@ -92,7 +96,7 @@ class DecimalRangeSource(ParamSource):
             last_str = None
 
         first_value = int(first_str)
-        last_value = int(last_str) if last_str is not None else "9" * len(first_str)
+        last_value = int(last_str if last_str is not None else "9" * len(first_str))
         return cls(num_digits=len(first_str), first_value=first_value, last_value=last_value)
 
 class RandomDigitSource(DecimalRangeSource):