resolveOrCreate method
Finds the variable with the given name, either within this scope or an ancestor. Creates a new variable if none was found.
If a new variable is created, you may optionally give it a value
.
You can also mark the new variable as a constant
.
Implementation
Variable<T> resolveOrCreate(String name, {T? value, bool? constant}) {
var resolved = resolve(name);
if (resolved != null) return resolved;
return create(name, value: value, constant: constant);
}