arg1 : STRING
         | NUMBER
         | IDENT
         | GLOBAL

def p_arg1(p):
    """
    arg1 : STRING
         | NUMBER
         | IDENT
         | GLOBAL
    """
    # a hack to support "clear global"
    p[0] = node.string(value=str(p[1]), lineno=p.lineno(1), lexpos=p.lexpos(1))