Num repeats challenge

num_repeats.rb

irb(main):089:0> def num_repeats(string)
irb(main):090:1> counts = {}
irb(main):091:1> string.each_char{|k|counts[k] ||=0; counts[k] +=1}
irb(main):092:1> counts.select{|k,v| v > 1 }.length
irb(main):093:1> end
=> :num_repeats
irb(main):094:0> num_repeats
ArgumentError: wrong number of arguments (0 for 1)
	from (irb):89:in `num_repeats'
	from (irb):94
	from /Users/ross/.rubies/ruby-2.1.6/bin/irb:11:in `<main>'
irb(main):095:0> num_repeats("google")
=> 2
irb(main):096:0> class Foo
irb(main):097:1>   def num_repeats(string)
irb(main):098:2>     string.length
irb(main):099:2>   end
irb(main):100:1> end
=> :num_repeats
irb(main):101:0> num_repeats("google")
=> 2
irb(main):102:0> Foo
=> Foo
irb(main):103:0> foo = Foo.new
=> #<Foo:0x007fe8aba560e0>
irb(main):104:0> foo.num_repeats
ArgumentError: wrong number of arguments (0 for 1)
	from (irb):97:in `num_repeats'
	from (irb):104
	from /Users/ross/.rubies/ruby-2.1.6/bin/irb:11:in `<main>'
irb(main):105:0> foo.num_repeats "google"
=> 6
irb(main):106:0>