def eval(cls, arg):
     if not arg.is_Atom:
         c, arg_ = factor_terms(arg).as_coeff_Mul()
         if arg_.is_Mul:
             arg_ = Mul(*[a if (sign(a) not in (-1, 1)) else
                 sign(a) for a in arg_.args])
         arg_ = sign(c)*arg_
     else:
         arg_ = arg
     x, y = re(arg_), im(arg_)
     rv = atan2(y, x)
     if rv.is_number and not rv.atoms(AppliedUndef):
         return rv
     if arg_ != arg:
         return cls(arg_, evaluate=False)

 def eval(cls, arg):
     if isinstance(arg, exp_polar):
         return periodic_argument(arg, oo)
     if not arg.is_Atom:
         c, arg_ = factor_terms(arg).as_coeff_Mul()
         if arg_.is_Mul:
             arg_ = Mul(*[a if (sign(a) not in (-1, 1)) else
                 sign(a) for a in arg_.args])
         arg_ = sign(c)*arg_
     else:
         arg_ = arg
     if arg_.atoms(AppliedUndef):
         return
     x, y = arg_.as_real_imag()
     rv = atan2(y, x)
     if rv.is_number:
         return rv
     if arg_ != arg:
         return cls(arg_, evaluate=False)

 def _eval_rewrite_as_atan2(self, arg, **kwargs):
     x, y = self.args[0].as_real_imag()
     return atan2(y, x)

 def _eval_rewrite_as_atan2(self, arg):
     x, y = re(self.args[0]), im(self.args[0])
     return atan2(y, x)

def test_sympy__functions__elementary__trigonometric__atan2():
    from sympy.functions.elementary.trigonometric import atan2
    assert _test_args(atan2(2, 3))