code: def build(self, stmts=None, set_check_var=True, invert=False):
          
          out = ""
          if set_check_var:
              out += self.check_var + " = False\n"
          out += self.out()
          if stmts is not None:
              out += "if " + ("not " if invert else "") + self.check_var + ":" + "\n" + openindent + "".join(stmts) + closeindent
          return out
docs: Construct code for performing the match then executing stmts.