string or forward range of characters
string of characters to be sliced off front of str[]
slice of str
assert(chompPrefix("hello world", "he") == "llo world"); assert(chompPrefix("hello world", "hello w") == "orld"); assert(chompPrefix("hello world", " world") == "hello world"); assert(chompPrefix("", "hello") == "");
If str starts with delimiter, then the part of str following delimiter is returned. If str does not start with
delimiter, then it is returned unchanged.