1 10/17/84  reverse_verify, rvverify
 2 
 3 Syntax as a command:  rvverify STRA STRB
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 5 
 6 Syntax as an active function:  [rvverify STRA STRB]
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 8 
 9 Function:  performs the same function as the verify active function,
10 but in reverse order.
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12 
13 Notes:  The active function returns the index (character position) of
14 the last character in STRA that does not appear in STRB (verify returns
15 the first such character).  If all characters of STRA appear in STRB, 0
16 is returned.
17    [reverse_verify STRA STRB]
18 is the same as--
19    [length STRA] - [verify [reverse STRA] STRB] + 1
20 when the characters of STRA do not appear in STRB.  It is 0 when all
21 characters of STRA appear in STRB.