权限控制
主要类为Ownable和AccessControl，AccessControl管理角色
Ownable包含修改器onlyOwner
modifieronlyOwner(){_checkOwner();_;}function_checkOwner()internal view virtual{if(owner()!=_msgSender()){revertOwnableUnauthorizedAccount(_msgSender());}}AccessControl包含修改器onlyRole
modifieronlyRole(bytes32 role){_checkRole(role);_;}function_checkRole(bytes32 role)internal view virtual{_checkRole(role,_msgSender());}function_checkRole(bytes32 role,address account)internal view virtual{if(!hasRole(role,account)){revertAccessControlUnauthorizedAccount(account,role);}}
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