def add(values)
      values.each do |key, val|
        k_sym = key.to_sym
        fail Override, "Property :#{key} already present" if respond_to?(k_sym)
        define_singleton_method(k_sym) { val }
      end
    end
def add(values)
      values.each do |key, val|
        k_sym = key.to_sym
        fail Override, "Property :#{key} already present" if respond_to?(k_sym)
        define_singleton_method(k_sym) { val }
      end
    end
Context constructor.

 @param values [Hash]
 Method `add` allows adding new properties (as a Hash) to the Context.

 @param values [Hash]