<a href="https://solidity.readthedocs.io/en/v0.6.2/contracts.html#receive-ether-function" class="" title="the link to documentation" target="_blank">
title="A contract can have at most one receive function, declared using receive() external payable { ... } and one fallback function, declared using fallback () external [payable].
These functions cannot have arguments, cannot return anything. Receive is executed on a call to the contract with empty calldata on plain Ether transfers (e.g. via .send() or .transfer()).
</a>
If no such function exists, but a payable fallback function exists, the fallback function will be called on a plain Ether transfer. If neither a receive Ether nor a payable fallback function is present, the contract cannot receive Ether through regular transactions and throws an exception.
Fallback is executed on a call to the contract if none of the other functions match the given function signature."
