The string(s) to search for. By default allows POSIX 1003.2
regular expressions. Use perl = TRUE for perl-style regex, or
fixed = TRUE for fixed strings.
Accepts single strings or a character vector of strings.
search_in
The name of the column to search in. Accepts single strings
or a character vector of column names. If NULL, searches all columns.
verbose
If TRUE, prints console messages on data retrieval progress.
Defaults to TRUE.