awesome_nested_set_sample.rb

# Create a root node:
science = Category.create!(name: 'Science')

# Put a new thing inside this root node:
physics = Category.create!(name: 'Physics')
physics.move_to_child_of(science)

# Put another thing inside the "physics" node:
gravity = Category.create!(name: 'Gravity')
gravity.move_to_child_of(physics)

# Reload the root node:
science.reload

# Now you should have something that resembles this:
#    science
#    '-- physics
#        '-- gravity