earth = Space('Earth')
mars = Space('Mars')
solar_system.add_element(mercury)
solar_system.add_element(venus)
solar_system.add_element(earth)
solar_system.add_element(mars)
moon = Space('Moon')
earth.add_element(moon)
lunohod = Space('Lunohod')
moon.add_element(lunohod)
phobos = Space('Phobos')
phobos2 = Space('Phobos')
phobos3 = Space('Phobos')
deimos = Space('Deimos')
mars.add_element(phobos)
mars.add_element(phobos2)
mars.add_element(phobos3)
mars.add_element(deimos)
phobos.detach_from_parent()
earth.add_element(phobos)
phobos.detach_from_parent()
mars.add_element(phobos)
solar_system.print_tree()
mars.remove_element(lunohod)
print(phobos2.name)
