add function to receive file from user
add function to receive file from user

HuimingCheng/AutoGrading,Hubert51/AutoGrading,HuimingCheng/AutoGrading,Hubert51/AutoGrading,HuimingCheng/AutoGrading,Hubert51/AutoGrading,HuimingCheng/AutoGrading,HuimingCheng/AutoGrading,Hubert51/AutoGrading,Hubert51/AutoGrading