Preserve blank lines in code blocks with tabs:

    a code block
    
    two tabbed lines
    
    
    three tabbed lines
    
    
    
    four tabbed lines
    
    
    
    
    five tabbed lines
    
    
    
    
    
    six tabbed lines
    
    
    
    
    
    
    End of tabbed block
    
    
    
    
    
    
And without tabs:

    a code block

    two blank lines


    three blank lines



    four blank lines




    five blank lines





    six blank lines






    End of block






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