.rb

[1] pry(main)> class Foo
[1] pry(main)*   FOO = lambda { |v| some_instance_method(v) }  
[1] pry(main)*   def call_foo  
[1] pry(main)*     FOO.call(1)    
[1] pry(main)*   end    
[1] pry(main)*   
[1] pry(main)*   def some_instance_method(v)  
[1] pry(main)*     puts v    
[1] pry(main)*   end    
[1] pry(main)* end  
=> nil
[2] pry(main)> Foo.new.call_foo
NoMethodError: undefined method `some_instance_method' for Foo:Class
from (pry):2:in `__pry__'
[3] pry(main)> class Foo
[3] pry(main)*   def call_foo
[3] pry(main)*     instance_exec 1, &FOO
[3] pry(main)*   end  
[3] pry(main)* end  
=> nil
[4] pry(main)> Foo.new.call_foo
1
=> nil