add generic suf f

cadCAD_tools/__init__.py

@@ -1,2 +1,3 @@
 from cadCAD_tools.execution import easy_run
-from cadCAD_tools.profiling import profile_run
+from cadCAD_tools.profiling import profile_run
+from cadCAD_tools.utils import generic_suf

cadCAD_tools/utils.py

@@ -0,0 +1,17 @@
+from .types import Signal, StateUpdate, VariableUpdate
+
+def generic_suf(variable: str,
+                signal: str='') -> StateUpdate:
+    """
+    Generate a State Update Function that assigns the signal value to the 
+    given variable. By default, the signal has the same identifier as the
+    variable.
+    """
+    if signal is '':
+        signal = variable
+    else:
+        pass
+
+    def suf(_1, _2, _3, _4, signals: Signal) -> VariableUpdate:
+        return (variable, signals[signal])
+    return suf