code: def get_key(self, key, target='in'):
          
          target = 'out' if target == 'out' else 'in'
          return self.opt[key][self.style[target]]['name']
docs: Get the name of a key in current style.
          e.g.: in javadoc style, the returned key for 'param' is '@param'
  
          :param key: the key wanted (param, type, return, rtype,..)
          :param target: the target docstring is 'in' for the input or
            'out' for the output to generate. (Default value = 'in')