def valid?
      return false if @is_valid.nil?
      signature_implementation_validator = EnumAttributeValidator.new('String', ["Stamp", "Image", "Annotation", "Sticker", "TextToFormField", "Watermark"])
      return false unless signature_implementation_validator.valid?(@signature_implementation)
      return true
    end
def valid?
      return false if @is_valid.nil?
      signature_implementation_validator = EnumAttributeValidator.new('String', ["Stamp", "Image", "Annotation", "Sticker", "TextToFormField", "Watermark"])
      return false unless signature_implementation_validator.valid?(@signature_implementation)
      return true
    end
Check to see if the all the properties in the model are valid
 @return true if the model is valid