Function: isearch-occur

Run `occur' using the last search string as the regexp.
Interactively, REGEXP is constructed using the search string from the
last search command. NLINES has the same meaning as in `occur'.

If the last search command was a word search, REGEXP is computed from
the search words, ignoring punctuation. If the last search
command was a regular expression search, REGEXP is the regular
expression used in that search. If the last search command searched
for a literal string, REGEXP is constructed by quoting all the special characters in that string.