File exists but Python says 'not found'.

[prerit86 at gmail.com]

The variable 'train' is being called like this ->

def main(train='train.csv', test='test.csv', submit='logistic_pred.csv'):    
    print "Reading dataset..."
    train_data = pd.read_csv(train)
    test_data = pd.read_csv(test)

Let me know if I need to post the full code.