ident_init_opt : NEG
                   | ident
                   | ident EQ expr

def p_ident_init_opt(p):
    """
    ident_init_opt : NEG
                   | ident
                   | ident EQ expr
    """
    if p[1] == '~':
        p[0] = node.ident("__")
    else:
        p[0] = p[1]
    if len(p) == 2:
        p[0].init = node.ident(name="None")
    else:
        p[0].init = p[3]