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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_instance_assignment(self, ctx):
 """ Gets the integer expression in any of the four instance assignment operators ('=' '@' '+=' '%=') """

        if ctx is None:
            return None

        visitor = ExprVisitor(self.compiler)
        expr = visitor.visit(ctx.expr())
        expr = expressions.AssignmentCast(self.compiler.env, SourceRef.from_antlr(ctx.op), expr, int)
        expr.predict_type()
        return expr