How to assign hash['a']['b']= 'c' if hash['a'] doesn't exist?

Question

Is there any way simpler than

if hash.key?(\'a\')
  hash[\'a\'][\'b\'] = \'c\' 
else  
  hash[\'a\'] = {}
  hash[\'a\'][\'b\'] = \'c\' 
end

Answer 1

The question here: Is auto-initialization of multi-dimensional hash array possible in Ruby, as it is in PHP? provides a very useful AutoHash implementation that does this.