def make_json(obj)
      return JSON.parse(obj).to_json if obj.is_a?(String)
      return obj.to_json if obj.is_a?(Hash)
      return JSON.generate(obj).to_json
    rescue
      raise Mailgun::ParameterError, 'Provided data could not be made into JSON. Try a JSON string or Hash.', obj
    end
def make_json(obj)
      return JSON.parse(obj).to_json if obj.is_a?(String)
      return obj.to_json if obj.is_a?(Hash)
      return JSON.generate(obj).to_json
    rescue
      raise Mailgun::ParameterError, 'Provided data could not be made into JSON. Try a JSON string or Hash.', obj
    end
Private: given an object attempt to make it into JSON

 obj - an object. Hopefully a JSON string or Hash

 Returns a JSON object or raises ParameterError