getFunction method
Returns a function of name
and parametersSignature
If parent is defined, will also look in the parent context.
Implementation
ASTFunctionDeclaration? getFunction(
String name, ASTFunctionSignature parametersSignature) {
var f = block.getFunction(name, parametersSignature, this);
if (f != null) return f;
return parent?.getFunction(name, parametersSignature);
}