Lesson 3: Conventions for Identifiers 

class ClassName

  def method_name (method_arg = nil)
    local_variable     = 42
    @instance_variable = 21
    @@class_variable   = 11.5
    a_hash = { :symbol1 => 'one', :symbol2 => 'two' }
    a_hash[:symbol3] = 'three'
  end

end