more in the spirit of TMTOWTDI:

UPDATE: I should have used the character class [a-z] instead of \l\w in the first part of the regex, that way numbers, uppercase characters and underscores wouldn't be matched. it would still work either way, though.

if (/(\l\w)(?{local $lastchar = ord $1;})(??{chr(++$lastchar)}){4}/) {
   # INSERT YOUR CODE HERE
}
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