def test_isfloat_returns_False_for_strings(x): assert not isfloat(x)
def test_isfloat_returns_True_for_real_numbers(x): assert isfloat(x)
def test_isfloat_returns_False_for_strings_example(): assert not isfloat('45.8') assert not isfloat('invalid')
def test_isfloat_returns_True_for_real_numbers_example(): assert isfloat(-45.0) assert isfloat(45.8e-2)