print("...took %d ms" % ms)

    print("\nApplying the constraint...")
    t.start()

    mols = idcons.update(system)

    ms = t.elapsed()

    print("...took %d ms" % ms)

    return mols

centers = []

for i in range(0,system.nMolecules()):
    centers.append( cljff[MolIdx(i)].evaluate().center() )

def printMolecules(mols):
    for molnum in mols.molNums():
        mol = mols[molnum]
        print(molnum, mol, mol.evaluate().center())

print("\nHere are the coordinates of the centers of molecules 10 and 20")
print(centers[10], centers[20])

print("\nTesting centers[0], centers[1]")
mols = testConstraint( [centers[0], centers[1]], system )
print(mols)
printMolecules(mols)