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() => switch ((real, imag)) {
(0, final im) => '${im}i',
(final re, 0) => '$re',
(final re, final im) when im > 0 => '$re + ${im}i',
(final re, final im) => '$re - ${im.abs()}i',
};