<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _check_R2_axes_asym(self):
 """ Test for 2-fold rotation along the principal axes. Used to handle asymetric top molecules. """

        for v in self.principal_axes:
            op = SymmOp.from_axis_angle_and_translation(v, 180)
            if self.is_valid_op(op):
                self.symmops.append(op)
                self.rot_sym.append((v, 2))