code: def only(self, arguments):
          
          data = {}
          if not isinstance(arguments, list):
              arguments = list(arguments)
  
          for i in arguments:
              data[i] = self.get_argument(i)
          return data
docs: returns the key, value pair of the arguments passed as a dict object
  
          Sample Usage
          ++++++++++++++
          .. code:: python
  
              from bast import Controller
  
              class MyController(Controller):
                  def index(self):
                      data = self.only(['username'])
  
          Returns only the argument username and assigns it to the data variable.