use NotImplementedError for raising exception

wrappers/python/simtk/openmm/app/charmmpsffile.py

@@ -342,7 +342,7 @@ class CharmmPsfFile(object):
             # We have a CHARMM PSF file; now do NUMLP/NUMLPH sections
             numlp, numlph = psfsections['NUMLP NUMLPH'][0]
             if numlp != 0 or numlph != 0:
-                raise NotImplemented('Cannot currently handle PSFs with lone '
+                raise NotImplementedError('Cannot currently handle PSFs with lone '
                                           'pairs defined in the NUMLP/NUMLPH '
                                           'section.')
         # Now do the CMAPs

wrappers/python/simtk/openmm/app/gromacstopfile.py

@@ -890,7 +890,7 @@ class GromacsTopFile(object):
 
                     if has_nbfix_terms:
                         if self._defaults[1] != '2':
-                            raise NotImplemented('NBFIX terms with LB combination rule is not yet supported')
+                            raise NotImplementedError('NBFIX terms with LB combination rule is not yet supported')
                         nb.addParticle(q, 1.0, 0.0)
                         atom_charges.append(q)
                     else:
@@ -1054,7 +1054,7 @@ class GromacsTopFile(object):
 
         if has_nbfix_terms:
             if self._defaults[1] != '2':
-                raise NotImplemented('NBFIX terms with LB combination rule is not yet supported')
+                raise NotImplementedError('NBFIX terms with LB combination rule is not yet supported')
 
             atom_nbfix_types = set([])
             for pair in self._nonbondTypes:

wrappers/python/simtk/openmm/app/internal/charmm/topologyobjects.py

@@ -531,7 +531,7 @@ class ResidueList(list):
         return atom
 
     def append(self, thing):
-        raise NotImplemented('Use "add_atom" to build a residue list')
+        raise NotImplementedError('Use "add_atom" to build a residue list')
 
     extend = append