gistfile1.rb

➜  ~  irb
1.9.3p194 :001 > @args = {"foo"=>2}
 => {"foo"=>2} 
1.9.3p194 :002 > :@args
 => :@args 
1.9.3p194 :003 > instance_variable_defined?
instance_variable_defined?
1.9.3p194 :003 > instance_variable_defined? :@args
 => true 
1.9.3p194 :004 > instance_variable_defined? :@argss
 => false 
1.9.3p194 :005 > instance_variable_defined? :args
NameError: `args' is not allowed as an instance variable name
	from (irb):5:in `instance_variable_defined?'
	from (irb):5
	from /Users/keyvan/.rvm/rubies/ruby-1.9.3-p194/bin/irb:16:in `<main>'
1.9.3p194 :006 > instance_variable_defined? :@args
 => true 
1.9.3p194 :007 >