{ERC20} token, including: - Preminted initial supply - Ability for holders to burn (destroy) their tokens - No access control mechanism (for minting/pausing) and hence no governance This contract uses {ERC20Burnable} to include burn capabilities - head to its documentation for details. _Available since v3.4._

Contract module which allows children to implement an emergency stop mechanism that can be triggered by an authorized account. This module is used through inheritance. It will make available the modifiers `whenNotPaused` and `whenPaused`, which can be applied to the functions of your contract. Note that they will not be pausable by simply including this module, only once the modifiers are put in place.

Contract module which provides a basic access control mechanism, where there is an account (an owner) that can be granted exclusive access to specific functions. By default, the owner account will be the one that deploys the contract. This can later be changed with {transferOwnership}. This module is used through inheritance. It will make available the modifier `onlyOwner`, which can be applied to your functions to restrict their use to the owner.

Contract module that allows children to implement role-based access control mechanisms. This is a lightweight version that doesn't allow enumerating role members except through off-chain means by accessing the contract event logs. Some applications may benefit from on-chain enumerability, for those cases see {AccessControlEnumerable}. Roles are referred to by their `bytes32` identifier. These should be exposed in the external API and be unique. The best way to achieve this is by using `public constant` hash digests: ``` bytes32 public constant MY_ROLE = keccak256("MY_ROLE"); ``` Roles can be used to represent a set of permissions. To restrict access to a function call, use {hasRole}: ``` function foo() public { require(hasRole(MY_ROLE, msg.sender)); ... } ``` Roles can be granted and revoked dynamically via the {grantRole} and {revokeRole} functions. Each role has an associated admin role, and only accounts that have a role's admin role can call {grantRole} and {revokeRole}. By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means that only accounts with this role will be able to grant or revoke other roles. More complex role relationships can be created by using {_setRoleAdmin}. WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to grant and revoke this role. Extra precautions should be taken to secure accounts that have been granted it.

Extension of {ERC20} that allows token holders to destroy both their own tokens and those that they have an allowance for, in a way that can be recognized off-chain (via event analysis).

Implementation of the {IERC20} interface. This implementation is agnostic to the way tokens are created. This means that a supply mechanism has to be added in a derived contract using {_mint}. For a generic mechanism see {ERC20PresetMinterPauser}. TIP: For a detailed writeup see our guide https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How to implement supply mechanisms]. We have followed general OpenZeppelin Contracts guidelines: functions revert instead returning `false` on failure. This behavior is nonetheless conventional and does not conflict with the expectations of ERC20 applications. Additionally, an {Approval} event is emitted on calls to {transferFrom}. This allows applications to reconstruct the allowance for all accounts just by listening to said events. Other implementations of the EIP may not emit these events, as it isn't required by the specification. Finally, the non-standard {decreaseAllowance} and {increaseAllowance} functions have been added to mitigate the well-known issues around setting allowances. See {IERC20-approve}.

Provides information about the current execution context, including the sender of the transaction and its data. While these are generally available via msg.sender and msg.data, they should not be accessed in such a direct manner, since when dealing with meta-transactions the account sending and paying for execution may not be the actual sender (as far as an application is concerned). This contract is only required for intermediate, library-like contracts.

Interface of the ERC20 standard as defined in the EIP.

Interface for the optional metadata functions from the ERC20 standard. _Available since v4.1._

External interface of AccessControl declared to support ERC165 detection.

String operations.

Implementation of the {IERC165} interface. Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check for the additional interface id that will be supported. For example: ```solidity function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) { return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId); } ``` Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.

Interface of the ERC165 standard, as defined in the https://eips.ethereum.org/EIPS/eip-165[EIP]. Implementers can declare support of contract interfaces, which can then be queried by others ({ERC165Checker}). For an implementation, see {ERC165}.