str into substrings.
pattern indicates delimiters that separate
the input into fields. The input data between the matches become
the fields themselves.stri_split_coll(str, pattern, n_max = -1L, omit_empty = FALSE,
  opts_collator = NULL)stri_opts_collator; NULL
for default settingsstr, pattern, n_max, and omit_empty.If n_max is negative (default), then all pieces are extracted.
omit_empty is applied during splitting: if set to TRUE,
then empty strings will never appear in the resulting vector.
This is a locale-sensitive text operation.
See stringi-search-coll for more details on
locale-sensitive text searching in 
%!==%,
  %!=%, %<=%< a="">=%<>,
  %<%< a="">%<>, %===%,
  %==%, %>=%,
  %>%, %stri!==%,
  %stri!=%, %stri<=%< a="">=%<>,
  %stri<%< a="">%<>, %stri===%,
  %stri==%, %stri>=%,
  %stri>%; stri_cmp,
  stri_cmp_eq, stri_cmp_equiv,
  stri_cmp_ge, stri_cmp_gt,
  stri_cmp_le, stri_cmp_lt,
  stri_cmp_neq,
  stri_cmp_nequiv,
  stri_compare;
  stri_count_coll;
  stri_detect_coll;
  stri_duplicated,
  stri_duplicated_any;
  stri_enc_detect2;
  stri_extract_all_coll,
  stri_extract_first_coll,
  stri_extract_first_coll,
  stri_extract_last_coll,
  stri_extract_last_coll;
  stri_extract_words;
  stri_locate_all_coll,
  stri_locate_first_coll,
  stri_locate_first_coll,
  stri_locate_last_coll,
  stri_locate_last_coll;
  stri_locate_boundaries;
  stri_locate_words;
  stri_opts_collator;
  stri_order, stri_sort;
  stri_replace_all_coll,
  stri_replace_first_coll,
  stri_replace_first_coll,
  stri_replace_last_coll,
  stri_replace_last_coll;
  stri_split_boundaries;
  stri_trans_tolower,
  stri_trans_totitle,
  stri_trans_toupper;
  stri_unique; stri_wrap;
  stringi-locale;
  stringi-search-collOther search_coll: stri_count_coll;
  stri_detect_coll;
  stri_extract_all_coll,
  stri_extract_first_coll,
  stri_extract_first_coll,
  stri_extract_last_coll,
  stri_extract_last_coll;
  stri_locate_all_coll,
  stri_locate_first_coll,
  stri_locate_first_coll,
  stri_locate_last_coll,
  stri_locate_last_coll;
  stri_replace_all_coll,
  stri_replace_first_coll,
  stri_replace_first_coll,
  stri_replace_last_coll,
  stri_replace_last_coll;
  stringi-search-coll;
  stringi-search
Other search_split: stri_split_boundaries;
  stri_split_charclass;
  stri_split_fixed;
  stri_split_lines,
  stri_split_lines1,
  stri_split_lines1;
  stri_split_regex; stri_split;
  stringi-search