# File lib/r10k/util/symbolize_keys.rb, line 13
      def symbolize_keys!(hash, recurse = false)
        hash.keys.each do |key|
          if key.is_a?(String)
            if hash.key?(key.to_sym)
              raise TypeError, "An existing interned key for #{key} exists, cannot overwrite"
            end
            hash[key.to_sym] = hash.delete(key)
            key = key.to_sym
          end

          value = hash[key]
          if recurse && value.is_a?(Hash)
            symbolize_keys!(value, true)
          end
        end
      end