startswith["abcd";"ab"]
1
  startswith["abcd";"bc"]
0
  endswith["abcd";"cd"]
1
  endswith["abcd";"bc"]
0
  contains["abcdef";"cde"]
1
  contains["abcdef";"bdef"]
0
  _ss["abcdabceabc";"abc"]    / location of matches
0 4 8