code: def get_var(self, name):
          
          if name not in self._vars:
              raise VarNotDefinedError
  
          return self._vars[name]
docs: Retrieve a variable assigned to this user
          :param name: The name of the variable to retrieve
          :type  name: str
  
          :rtype: str
  
          :raises VarNotDefinedError: The requested variable has not been defined