methods_in_main.rb

def self.some_func
end

# now we can call this at the top-level
p some_func #=> nil

# without polluting Object
p Object.new.respond_to?(:some_func, true) #=> false

def some_object_polluting_func
end

# that also makes the method available at the top-level
p some_object_polluting_func #=> nil

# but it pollutes Object
p Object.new.respond_to?(:some_object_polluting_func, true) #=> true