def remove_vowels(text):
    """
    remove_vowels is a function that takes string and returns string without vowels.
    >>> remove_vowels('')
    ''
    >>> remove_vowels("abcdef\\nghijklm")
    'bcdf\\nghjklm'
    >>> remove_vowels('abcdef')
    'bcdf'
    >>> remove_vowels('aaaaa')
    ''
    >>> remove_vowels('zbcd')
    'zbcd'
    
    Example solution:
    # line 1
    vowels = 'aeiou'
    # line 2
    ret = ''
    # line 3
    for c in text:
        # line 4
        if c.lower() in vowels:
            # line 5
            ret += c
    # line 6
    return ret
    
    """
    # Please print out which line of the above program contains an error. E.g. if the bug is on line 4 then print 4
    # END OF CONTEXT
    print("4")
    # END OF SOLUTION

def check(candidate):

    import io
    from contextlib import redirect_stdout

    f = io.StringIO()
    with redirect_stdout(f):
        candidate('')
    out = f.getvalue().strip('\n')

    assert "4" == out
    for i in range(0, 10):
        if i != 4:
            assert str(i) != out

if __name__ == '__main__':
    check(remove_vowels)
