implemented 1st task
Merge branch '1st' into develop
implemented 2nd task
Merge branch 'feature_2nd' into develop
implemented 3rd task
Merge branch 'feature_3rd' into develop
implemented 4th task
Merge branch 'feature_4th' into develop
implemented 5th task
Merge branch 'feature_5th' into develop
implemented 6th task
implemented 7th task
Merge branch 'feature_7th' into develop
Merge branch 'develop'