def [](key)
      if @my_vars.include?(key)
        @my_vars[key]
      else
        @coa_vars.each do |coa_vars|
          if coa_vars.include?(key)
            @my_vars[key] = deep_dup(coa_vars[key])
            return @my_vars[key]
          end
        end
        nil
      end
    end
def [](key)
      if @my_vars.include?(key)
        @my_vars[key]
      else
        @coa_vars.each do |coa_vars|
          if coa_vars.include?(key)
            @my_vars[key] = deep_dup(coa_vars[key])
            return @my_vars[key]
          end
        end
        nil
      end
    end
Create a VarSet.

 @param vars [Hash] Optional initial variables.
 Access the value of variable.

 @param key [String, Symbol] The variable name.

 @return [Object] The variable's value.