docs: def convert_activity(ast):
      """Convert BEL1 activities to BEL2 act()"""
  
      if len(ast.args) > 1:
          log.error(f"Activity should not have more than 1 argument {ast.to_string()}")
  
      p_arg = ast.args[0]  # protein argument
      print("p_arg", p_arg)
      ma_arg = Function("ma", bo.spec)
      ma_arg.add_argument(StrArg(ast.name, ma_arg))
      p_arg.change_parent_fn(ma_arg)
      ast = Function("activity", bo.spec)
      p_arg.change_parent_fn(ast)
      ast.add_argument(p_arg)
      ast.add_argument(ma_arg)
  
      return ast