within static method
Returns the string bounded by the left and right delimiters.
Throws an ArgumentError exception if either of the delimiters
are missing.
If there are nested delimiters we return the outer most
delimiters.
final result= Strings.within("<AnInstance>", '<', '>');
result == 'AnInstance';
Implementation
static String within(String string, String left, String right) =>
Part.within(string, left, right);