search_for

      pattern: <string>
      replacement: <string>
      case sensitive flag: <yes/no>
      regular expression flag: <yes/no>
      enter folds setting: <never/if_open/always>
      enter virtual folds setting: <never/if_open/always>
      forwards flag: <yes/no>
      no of matches: <number>
      confirm flag: <yes/no>

 This command searches for a given pattern or regular expression and
 replaces it with a replacement string.

 It can be made to search nested folds and/or nested virtual folds,
 possibly discriminating on their open state.

 If the confirm flag is given, you are asked for confirmation on each
 substitution.

 It can be made to perform N substitutions too.

 The scope of the fold is the current fold.

 eg:  search_replace "fred" "bill" no no always always yes 1 no