def __call__(self, s):
        """Parse credentials from `s`.

        ("username" or "username:password").

        """
        try:
            return super().__call__(s)
        except argparse.ArgumentTypeError:
            # No password provided, will prompt for it later.
            return self.key_value_class(
                key=s,
                value=None,
                sep=SEPARATOR_CREDENTIALS,
                orig=s
            )
Parse credentials from `s`.

        ("username" or "username:password").

        
httpie/cli/argtypes.py