solidity events
// Solidity program to demonstrate
// creating an event
pragma solidity ^0.4.21;
// Creating a contract
contract eventExample {
// Declaring state variables
uint256 public value = 0;
// Declaring an event
event Increment(address owner);
// Defining a function for logging event
function getValue(uint _a, uint _b) public {
emit Increment(msg.sender);
value = _a + _b;
}
}