Since 0.2.7, --hidden now requires a value.

[Ryoga]

# v0.2.6
$ ./hgrep-v0.2.6-x86_64-apple-darwin/hgrep --help | grep hidden
    -., --hidden
            Search hidden files and directories. By default, hidden files and directories are
$ ./hgrep-v0.2.6-x86_64-apple-darwin/hgrep --hidden </dev/null

# v0.2.7
$ ./hgrep-v0.2.7-x86_64-apple-darwin/hgrep --help | grep hidden
  -., --hidden <hidden>
          Search hidden files and directories. By default, hidden files and directories are skipped
$ ./hgrep-v0.2.7-x86_64-apple-darwin/hgrep --hidden </dev/null
error: The argument '--hidden <hidden>' requires a value but none was supplied

For more information try '--help'