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| pragma solidity ^0.4.24;
import "./IERC20.sol"; import "../../math/SafeMath.sol";
contract ERC20 is IERC20 { using SafeMath for uint256;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowed;
uint256 private _totalSupply;
function totalSupply() public view returns (uint256) { return _totalSupply; }
function balanceOf(address owner) public view returns (uint256) { return _balances[owner]; }
function allowance( address owner, address spender ) public view returns (uint256) { return _allowed[owner][spender]; }
function transfer(address to, uint256 value) public returns (bool) { require(value <= _balances[msg.sender]); require(to != address(0));
_balances[msg.sender] = _balances[msg.sender].sub(value); _balances[to] = _balances[to].add(value); emit Transfer(msg.sender, to, value); return true; }
function approve(address spender, uint256 value) public returns (bool) { require(spender != address(0));
_allowed[msg.sender][spender] = value; emit Approval(msg.sender, spender, value); return true; }
function transferFrom( address from, address to, uint256 value ) public returns (bool) { require(value <= _balances[from]); require(value <= _allowed[from][msg.sender]); require(to != address(0));
_balances[from] = _balances[from].sub(value); _balances[to] = _balances[to].add(value); _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value); emit Transfer(from, to, value); return true; }
function increaseAllowance( address spender, uint256 addedValue ) public returns (bool) { require(spender != address(0));
_allowed[msg.sender][spender] = ( _allowed[msg.sender][spender].add(addedValue)); emit Approval(msg.sender, spender, _allowed[msg.sender][spender]); return true; }
function decreaseAllowance( address spender, uint256 subtractedValue ) public returns (bool) { require(spender != address(0));
_allowed[msg.sender][spender] = ( _allowed[msg.sender][spender].sub(subtractedValue)); emit Approval(msg.sender, spender, _allowed[msg.sender][spender]); return true; }
function _mint(address account, uint256 amount) internal { require(account != 0); _totalSupply = _totalSupply.add(amount); _balances[account] = _balances[account].add(amount); emit Transfer(address(0), account, amount); }
function _burn(address account, uint256 amount) internal { require(account != 0); require(amount <= _balances[account]);
_totalSupply = _totalSupply.sub(amount); _balances[account] = _balances[account].sub(amount); emit Transfer(account, address(0), amount); }
function _burnFrom(address account, uint256 amount) internal { require(amount <= _allowed[account][msg.sender]);
_allowed[account][msg.sender] = _allowed[account][msg.sender].sub( amount); _burn(account, amount); } }
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