Python: fix empty string output formatting

[TomBinford]

Running this Python code

print('a')
print('', end='')
print('b')

output:

expected output:

This is the cause. As far as I can tell received will always be true, when it should be false if text === ''.

TeachLAFrontend/src/util/languages/Python.js

Lines 6 to 16 in b4132fb

	let received;
	if (text !== '\\n') {
	received = true;
	} else if (received) {
	received = false;
	} else {
	received = true;
	}
	if (received) {
	mypre.value += `> ${text}`;
	}