human
Solve the following python programming problem given the following code:
@ assert_no_logs 
def test_linear_gradient() : 
    red = (1, 0, 0, 1) 
    lime = (0, 1, 0, 1) 
    blue = (0, 0, 1, 1) 
    pi = math.pi 
    def gradient(css, direction, colors = [blue], stop_positions = [None]) : 
        for (repeating, prefix) in ((False, ''), (True, 'repeating-')) : 
            expanded = expand_to_dict (('background-image: %slinear-gradient(%s)' % (prefix, css))) 
            [(_, [(type_, image)])] = expanded.items () 
            assert (type_ == 'linear-gradient') 
            assert isinstance (image, LinearGradient) 
            assert (image.repeating == repeating) 
            assert almost_equal ((image.direction_type, image.direction), direction) 
            assert almost_equal (image.colors, colors) 
            assert almost_equal (image.stop_positions, stop_positions) 
def invalid(css) : 
        assert_invalid (('background-image: linear-gradient(%s)' % css)) 
        assert_invalid (('background-image: repeating-linear-gradient(%s)' % css)) 
invalid (' ') 
    invalid ('1% blue') 
    invalid ('blue 10deg') 
    invalid ('blue 4') 
    invalid ('soylent-green 4px') 
    invalid ('red 4px 2px') 
    gradient ('blue', ('angle', pi)) 
    gradient ('red', ('angle', pi), [red], [None]) 
    gradient ('blue 1%, lime,red 2em ', ('angle', pi), [blue, lime, red], [(1, '%'), None, (2, 'em')]) 
    invalid ('18deg') 
    gradient ('18deg, blue', ('angle', (pi / 10))) 
    gradient ('4rad, blue', ('angle', 4)) 
    gradient ('.25turn, blue', ('angle', (blue / 2))) 
    gradient ('100grad, blue', ('angle', (pi / 2))) 
    gradient ('12rad, blue 1%, lime,red 2em ', ('angle', 12), [blue, lime, red], [(1, '%'), None, (2, 'em')]) 
    invalid ('10arc-minutes, blue') 
    invalid ('10px, blue') 
    invalid ('to 90deg, blue') 
    gradient ('to top, blue', ('angle', 0)) 
    gradient ('to right, blue', ('angle', (pi / 2))) 
    gradient ('to bottom, blue', ('angle', pi)) 
    gradient ('to left, blue', ('angle', ((pi * 3) / 2))) 
    gradient ('to right, blue 1%, lime,red 2em ',...

    
    

    Fix the buggy line: gradient ('.25turn, blue', ('angle', (blue / 2)))
assistant
#Here is Python program to fix the buggy line: gradient ('.

gradient ('.25turn, blue', ('angle', (pi / 2)))