remove default when action is store_true in arguments

examples/run_lm_finetuning.py

@@ -432,7 +432,6 @@ def main():
                              "Sequences longer than this will be truncated, and sequences shorter \n"
                              "than this will be padded.")
     parser.add_argument("--do_train",
-                        default=False,
                         action='store_true',
                         help="Whether to run training.")
     parser.add_argument("--train_batch_size",
@@ -457,11 +456,9 @@ def main():
                         help="Proportion of training to perform linear learning rate warmup for. "
                              "E.g., 0.1 = 10%% of training.")
     parser.add_argument("--no_cuda",
-                        default=False,
                         action='store_true',
                         help="Whether not to use CUDA when available")
     parser.add_argument("--on_memory",
-                        default=False,
                         action='store_true',
                         help="Whether to load train samples into memory or use disk")
     parser.add_argument("--local_rank",
@@ -477,7 +474,6 @@ def main():
                         default=1,
                         help="Number of updates steps to accumualte before performing a backward/update pass.")
     parser.add_argument('--fp16',
-                        default=False,
                         action='store_true',
                         help="Whether to use 16-bit float precision instead of 32-bit")
     parser.add_argument('--loss_scale',