code: def pass_bracket(source, start, bracket='()'):
      
      e = bracket_split(source[start:], [bracket], False)
      try:
          cand = e.next()
      except StopIteration:
          return None, None
      if not cand.strip():  #white space...
          try:
              res = e.next()
              return res, start + len(cand) + len(res)
          except StopIteration:
              return None, None
      elif cand[-1] == bracket[1]:
          return cand, start + len(cand)
      else:
          return None, None
docs: Returns content of brackets with brackets and first pos after brackets
       if source[start] is followed by some optional white space and brackets.
       Otherwise None