global_list : ident
                   | global_list ident

def p_global_list(p):
    """global_list : ident
                   | global_list ident
    """
    if len(p) == 2:
        p[0] = node.global_list([p[1]])
    elif len(p) == 3:
        p[0] = p[1]
        p[0].append(p[2])