docs: def convert_tloc(ast):
      """Convert BEL1 tloc() to BEL2"""
  
      from_loc_arg = ast.args[1]
      to_loc_arg = ast.args[2]
      from_loc = Function("fromLoc", spec, parent_function=ast)
      from_loc.add_argument(
          NSArg(from_loc_arg.namespace, from_loc_arg.value, parent_function=from_loc)
      )
      to_loc = Function("toLoc", spec, parent_function=ast)
      to_loc.add_argument(
          NSArg(to_loc_arg.namespace, to_loc_arg.value, parent_function=to_loc)
      )
  
      ast.args[1] = from_loc
      ast.args[2] = to_loc
  
      return ast