async def verifymessage(self, address, signature, message):
        """Verify a signature.

        arg:str:address:Bitcoin address
        arg:str:message:Clear text message. Use quotes if it contains spaces.
        arg:str:signature:The signature, base64-encoded.
        """
        try:
            sig = base64.b64decode(signature, validate=True)
        except binascii.Error:
            return False
        message = util.to_bytes(message)
        return bitcoin.verify_usermessage_with_address(address, sig, message)
Verify a signature.

        arg:str:address:Bitcoin address
        arg:str:message:Clear text message. Use quotes if it contains spaces.
        arg:str:signature:The signature, base64-encoded.
        
electrum/commands.py