commands: remove default=None from argparse add_argument calls

Per https://github.com/iterative/dvc/pull/2112#pullrequestreview-255013079

dvc/command/cache.py

@@ -57,7 +57,6 @@ def add_parser(subparsers, parent_parser):
     )
     cache_dir_parser.add_argument(
         "value",
-        default=None,
         help="Path to cache directory. Relative paths are resolved relative "
         "to the current directory and saved to config relative to the "
         "config file location.",

dvc/command/config.py

@@ -74,7 +74,5 @@ def add_parser(subparsers, parent_parser):
         help="Unset option.",
     )
     config_parser.add_argument("name", help="Option name.")
-    config_parser.add_argument(
-        "value", nargs="?", default=None, help="Option value."
-    )
+    config_parser.add_argument("value", nargs="?", help="Option value.")
     config_parser.set_defaults(func=CmdConfig)

dvc/command/data_sync.py

@@ -101,11 +101,7 @@ def shared_parent_parser():
         add_help=False, parents=[get_parent_parser()]
     )
     shared_parent_parser.add_argument(
-        "-j",
-        "--jobs",
-        type=int,
-        default=None,
-        help="Number of jobs to run simultaneously.",
+        "-j", "--jobs", type=int, help="Number of jobs to run simultaneously."
     )
     shared_parent_parser.add_argument(
         "--show-checksums",

dvc/command/diff.py

@@ -144,7 +144,6 @@ def add_parser(subparsers, parent_parser):
     diff_parser.add_argument(
         "-t",
         "--target",
-        default=None,
         help=(
             "Source path to a data file or directory. Default None. "
             "If not specified, compares all files and directories "
@@ -161,6 +160,5 @@ def add_parser(subparsers, parent_parser):
             "diff shows the difference between current HEAD and a_ref"
         ),
         nargs="?",
-        default=None,
     )
     diff_parser.set_defaults(func=CmdDiff)

dvc/command/gc.py

@@ -94,11 +94,7 @@ def add_parser(subparsers, parent_parser):
         help="Force garbage collection - automatically agree to all prompts.",
     )
     gc_parser.add_argument(
-        "-j",
-        "--jobs",
-        type=int,
-        default=None,
-        help="Number of jobs to run simultaneously.",
+        "-j", "--jobs", type=int, help="Number of jobs to run simultaneously."
     )
     gc_parser.add_argument(
         "-p",
@@ -106,7 +102,6 @@ def add_parser(subparsers, parent_parser):
         dest="repos",
         type=str,
         nargs="*",
-        default=None,
         help="Keep data files required by these projects "
         "in addition to the current one. "
         "Useful if you share a single cache across repos.",

dvc/command/run.py

@@ -130,12 +130,11 @@ def add_parser(subparsers, parent_parser):
         "-f", "--file", help="Specify name of the DVC-file it generates."
     )
     run_parser.add_argument(
-        "-c", "--cwd", default=None, help="Deprecated, use -w and -f instead."
+        "-c", "--cwd", help="Deprecated, use -w and -f instead."
     )
     run_parser.add_argument(
         "-w",
         "--wdir",
-        default=None,
         help="Directory within your repo to run your command in.",
     )
     run_parser.add_argument(