copy method
Returns a shallow copy of the receiver.
Override this method in all subclasses, return its own type.
Implementation
@override
SequenceParser9<R1, R2, R3, R4, R5, R6, R7, R8, R9> copy() =>
SequenceParser9<R1, R2, R3, R4, R5, R6, R7, R8, R9>(
parser1,
parser2,
parser3,
parser4,
parser5,
parser6,
parser7,
parser8,
parser9,
);