Get position of paired brackets in a string

Get position of the other paired bracket (nested) in a string

POS2 = GETBRACKETPAIRpos1(STR,POS1) gets the bracket pos1ition in a
string given the position of the other paired bracket.

Input:
STR : string (can be a nested string)
POS1: pos1ition of a bracket (can be either left or right)

Note:
1. Any bracket of '{[(<>)]}' can be recognized.
2. Input position can be either left or right bracket.
3. Mixed pair types are sup