Expected 
- $SUBSTRING(abcdef,3,5)=|cdef|
 
- $SUBSTRING(abcdefgh,3,5)=|cdefg|
 
- $SUBSTRING(abcdefgh,8,5)=|h|
 
- $SUBSTRING(abcdefgh,9,5)=||
 
- $SUBSTRING(abcdefg,-2,2)=|fg|
 
- $SUBSTRING(abcdefg,-1,2)=|g|
 
- $SUBSTRING(abcdefg,-7,2)=|ab|
 
- $SUBSTRING(abcdefg,-8,2)=||
 
- $SUBSTRING(abcdefg,0,2)=||
 
- $SUBSTRING(abcdefg,1,2)=|ab|
 
- $SUBSTRING(abcdefg,2,2)=|bc|
 
- $SUBSTRING(abcdefg,2,-1)=|bcdef|
 
- $SUBSTRING(abcdefg,-2,-1)=|f|
 
- $SUBSTRING(abc,def,3,3)=|c,d|
 
- $SUBSTRING(abcdefg)=||
 
- $SUBSTRING()=||
 
 
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 Actual 
 
-  $SUBSTRING(abcdef,3,5)=|cdef|
  -  $SUBSTRING(abcdefgh,3,5)=|cdefg|
  -  $SUBSTRING(abcdefgh,8,5)=|h|
  -  $SUBSTRING(abcdefgh,9,5)=||
  -  $SUBSTRING(abcdefg,-2,2)=|fg|
  -  $SUBSTRING(abcdefg,-1,2)=|g|
  -  $SUBSTRING(abcdefg,-7,2)=|ab|
  -  $SUBSTRING(abcdefg,-8,2)=||
  -  $SUBSTRING(abcdefg,0,2)=||
  -  $SUBSTRING(abcdefg,1,2)=|ab|
  -  $SUBSTRING(abcdefg,2,2)=|bc|
  -  $SUBSTRING(abcdefg,2,-1)=|bcdef|
  -  $SUBSTRING(abcdefg,-2,-1)=|f|
  -  $SUBSTRING(abc,def,3,3)=|c,d|
  -  $SUBSTRING(abcdefg)=||
  -  $SUBSTRING()=||
   
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