Concatenation and Repetition

Code
RegexSolverClient client = RegexSolverClient.builder()
    .apiToken(System.getenv("REGEXSOLVER_API_TOKEN"))
    .build();
Term a = Term.regex("ab");
Term b = Term.regex("c.*");
Term c = Term.regex("de");

OperationOptions operationOptions = OperationOptions.builder()
        .responseFormat(ResponseFormat.REGEX);
Term result = client.concat(List.of(a, b, c), operationOptions);

System.out.println(result); // regex=abc.*de

Code
RegexSolverClient client = RegexSolverClient.builder()
    .apiToken(System.getenv("REGEXSOLVER_API_TOKEN"))
    .build();
Term term = Term.regex("abc");

OperationOptions operationOptions = OperationOptions.builder()
        .responseFormat(ResponseFormat.REGEX);

Term r1 = client.repeat(term, 2, 4, operationOptions);
System.out.println(r1); // regex=(abc){2,4}

Term r2 = client.repeat(term, 1, null, operationOptions);
System.out.println(r2); // regex=(abc)+