fn abc(a ?map[string]string) ?string {
	return a?['foo']
}

fn abc_2(a ?map[string]string) ?string {
	return a?['foo']
}

fn test_option_map() {
	mut var4 := ?map[string]string{}
	assert var4 == none
	var4 = {
		'': ''
	}
	var4?['foo'] = 'foo'
	assert abc(var4)? == 'foo'
	assert abc_2(var4)? == 'foo'
	assert var4 != none
	assert var4? == {
		'':    ''
		'foo': 'foo'
	}
}