[Just_Harry]

It's valid in PowerShell, if "." is defined as a function:

  PS> function . {$Args}
  PS> . . .
  .

The first dot is an operator which invokes a command in the current scope, the second dot is our command ".", and the third dot is passed to the command as a string.

[trealira]

You can also do this in Bash.

  $ .(){ "$@"; } # define function called "."
  $ . . . # nothing
  $ . echo hello
  hello
  $