make python functions examples more complete by adding exception handling and initializing variables

examples/python/funcs.py

@@ -9,6 +9,7 @@ def loop(N,cut0,thresh,lmpptr):
   lmp = lammps(ptr=lmpptr)
   natoms = lmp.get_natoms()
 
+  try:
     for i in range(N):
       cut = cut0 + i*0.1
 
@@ -22,3 +23,6 @@ def loop(N,cut0,thresh,lmpptr):
       pe = lmp.extract_compute("thermo_pe",0,0)   # extract total PE from LAMMPS
       print("PE",pe/natoms,thresh)
       if pe/natoms < thresh: return
+  except Exception as e:
+    print("LOOP error:", e)
+

examples/python/in.python

@@ -28,6 +28,7 @@ python          simple here """
 from __future__ import print_function
 
 def simple():
+  foo = 0
   print("Inside simple function")
   try:
     foo += 1