code: def func_arg(self):
      localctx = LaTeXParser.Func_argContext(
          self, self._ctx, self.state
      )
      self.enterRule(localctx, 70, self.RULE_func_arg)
      try:
          self.state = 491
          self._errHandler.sync(self)
          la_ = self._interp.adaptivePredict(self._input, 56, self._ctx)
          if la_ == 1:
              self.enterOuterAlt(localctx, 1)
              self.state = 486
              self.expr()
              pass
  
          elif la_ == 2:
              self.enterOuterAlt(localctx, 2)
              self.state = 487
              self.expr()
              self.state = 488
              self.match(LaTeXParser.T__0)
              self.state = 489
              self.func_arg()
              pass
  
      except RecognitionException as re:
          localctx.exception = re
          self._errHandler.reportError(self, re)
          self._errHandler.recover(self, re)
      finally:
          self.exitRule()
      return localctx
  
imports: from antlr4 import *
  from io import StringIO
  import sys
label_desc: Use image node_id 37 for calling the LaTeXParser obj's underlying member method code with example usage: obj.func_arg() and returns: localctx