addFunction method
Add function to the current node.
Implementation
void addFunction(String tex, List<TeXArg> args) {
currentNode.removeCursor();
final func = TeXFunction(tex, currentNode, args);
/// Adding a pow requires further action, that's why we handle it in it's
/// own function.
if (tex.startsWith('^')) {
addPow(func);
}
// The same applies for fractions.
else if (tex == r'\frac') {
addFrac(func);
} else {
currentNode.addTeX(func);
currentNode = func.argNodes.first;
}
currentNode.setCursor();
notifyListeners();
}