Two ways to write an "increment" method

1. As I did in another post:

inc = lambda do |x|
  eval "#{x} += 1"
end

a = 5

inc[:a]

puts a       #=> 6

2. Inspired here:

def inc(&blk)
  eval "#{yield} += 1", blk
end

x = 5
inc {:x}

puts x       #=> 6