def test_build():
    import numpy as np
    from ase import Atoms, Atom

    a = Atoms([Atom('Cu')])
    a.positions[:] += 1.0
    print(a.get_positions(), a.positions)
    a = a + a
    a += a
    a.append(Atom('C'))
    a += Atoms([])
    a += Atom('H', magmom=1)
    print(a.get_initial_magnetic_moments())
    print(a[0].number)
    print(a[[0, 1]].get_atomic_numbers())
    print(a[np.array([1, 1, 0, 0, 1, 0], bool)].get_atomic_numbers())
    print(a[::2].get_atomic_numbers())
    print(a.get_chemical_symbols())
    del a[2]
    print(a.get_chemical_symbols())
    del a[-2:]
    print(a.get_chemical_symbols())