Fix code for US#01
Implement tests for US#02
Fix code for US#02
Implement tests for US#03
Fix code for US#03
Implement tests for US#04
Fix code for US#04
Implement tests for US#05
Implement tests for US#06
Fix code for US#06
Implement tests for US#07
Implement tests for US#08
Fix code for US#08
Implement tests for US#09