Check for none statements

src/lctime/characterization/ngspice_subprocess.py

@@ -138,20 +138,25 @@ def simulate_cell(
             #assert False, "`voltage` must be either a float or {}".format(PieceWiseLinear)
 
     # Create SPICE description of the input voltage sources.
-    active_signal_source_statements = "\n".join(
-        (
-            create_voltage_source_statement(net, wave)
-            for net, wave in input_voltages_active.items()
+
+    vcc_statement = create_voltage_source_statement(net, wave)
+    if vcc_statement not None:
+        active_signal_source_statements = "\n".join(
+            (
+                vcc_statement
+                for net, wave in input_voltages_active.items()
+            )
         )
-    )
 
     # Static inputs.
-    static_signal_source_statements = "\n".join(
-        (
-            create_voltage_source_statement(net, voltage)
-            for net, voltage in input_voltages_static.items()
+    vcc_statement = create_voltage_source_statement(net, voltage)
+    if vcc_statement not None:
+        static_signal_source_statements = "\n".join(
+            (
+                vcc_statement
+                for net, voltage in input_voltages_static.items()
+            )
         )
-    )
 
     # Load capacitance statements.
     if output_load_capacitances is None:
@@ -554,24 +559,28 @@ def simulate_cell_v2(
             return f"V{net} {net} {ground_net} PWL({voltage.to_spice_pwl_string()}) DC=0"
         elif isinstance(voltage, float):
             return f"V{net} {net} {ground_net} {voltage}"
-        else:
-            assert False, "`voltage` must be either a float or {}".format(PieceWiseLinear)
+        #else:
+        #    assert False, "`voltage` must be either a float or {}".format(PieceWiseLinear)
 
     # Create SPICE description of the input voltage sources.
-    active_signal_source_statements = "\n".join(
-        (
-            create_voltage_source_statement(net, wave)
-            for net, wave in input_voltages_active.items()
+    vcc_statement = create_voltage_source_statement(net, wave)
+    if vcc_statement not None:
+        active_signal_source_statements = "\n".join(
+            (
+                vcc_statement
+                for net, wave in input_voltages_active.items()
+            )
         )
-    )
 
     # Static inputs.
-    static_signal_source_statements = "\n".join(
-        (
-            create_voltage_source_statement(net, voltage)
-            for net, voltage in input_voltages_static.items()
+    vcc_statement = create_voltage_source_statement(net, voltage)
+    if vcc_statement not None:
+        static_signal_source_statements = "\n".join(
+            (
+                vcc_statement
+                for net, voltage in input_voltages_static.items()
+            )
         )
-    )
 
     # Load capacitance statements.
     if output_load_capacitances is None: