def test_parse_a_single_number(self):
     eq_(1, calculate("1"))
 def test_add_two_numbers(self):
     eq_(10, calculate("8+2"))
 def test_numbers_can_have_at_most_one_decimal_point(self):
     calculate("2.7.2")
 def test_parse_a_negative_number(self):
     eq_(-15, calculate("-15"))
 def test_parse_a_decimal_number(self):
     eq_(3.141, calculate("3.141"))