toString method
A string representation of this object.
Some classes have a default textual representation,
often paired with a static parse function (like int.parse).
These classes will provide the textual representation as
their string representation.
Other classes have no meaningful textual representation
that a program will care about.
Such classes will typically override toString to provide
useful information when inspecting the object,
mainly for debugging or logging.
Implementation
@override
String toString() {
  var leading = '';
  if (from != null) {
    leading = '($argument)';
  }
  String label;
  if (name case final name?) {
    label = name;
  } else {
    label = describeIdentity(this);
  }
  return '$label$leading';
}