operator: ssplit

    description:
        ssplit splits the superposition into a sequence
        ssplit["str"] splits the superposition into a sequence at the 'str' substring
      
    examples:
        ssplit |Fred>
            |F> . |r> . |e> . |d>
      
        ssplit (|a> + 2|bcd> + 3.1|efgh>)
            |a> . 2|b> . 2|c> . 2|d> . 3.1|e> . 3.1|f> . 3.1|g> . 3.1|h>      

        ssplit[", "] |a, b, c>
            |a> . |b> . |c>

        ssplit[" and "] |a, b, c and d>
            |a, b, c> . |d>

        ssplit[", "] ssplit[" and "] |a, b, c and d>
            |a> . |b> . |c> . |d>
    
    see also:
        split, smerge