code: def do_source(self, arg):
          
          try:
              obj = self._getval(arg)
          except Exception:
              return
          try:
              lines, lineno = getsourcelines(obj, self.get_locals(self.curframe))
          except (IOError, TypeError) as err:
              self.error(err)
              return
          self._print_lines(lines, lineno)
docs: source expression
          Try to get source code for the given object and display it.