Analyze the files contained in directory dirname.

        Args:
            dirname: directory path
            exclude_exts: list of file extensions that should be skipped.
            exclude_fnames: list of file names that should be skipped.

        Returns:
            List of pseudopotential objects.

def scan_directory(self, dirname, exclude_exts=(), exclude_fnames=()):
        """
        Analyze the files contained in directory dirname.

        Args:
            dirname: directory path
            exclude_exts: list of file extensions that should be skipped.
            exclude_fnames: list of file names that should be skipped.

        Returns:
            List of pseudopotential objects.
        """
        for i, ext in enumerate(exclude_exts):
            if not ext.strip().startswith("."):
                exclude_exts[i] =  "." + ext.strip()

        # Exclude files depending on the extension.
        paths = []
        for fname in os.listdir(dirname):
            root, ext = os.path.splitext(fname)
            path = os.path.join(dirname, fname)
            if (ext in exclude_exts or fname in exclude_fnames or
                fname.startswith(".") or not os.path.isfile(path)): continue
            paths.append(path)

        pseudos = []
        for path in paths:
            # Parse the file and generate the pseudo.
            try:
                pseudo = self.parse(path)
            except:
                pseudo = None

            if pseudo is not None:
                pseudos.append(pseudo)
                self._parsed_paths.extend(path)
            else:
                self._wrong_paths.extend(path)

        return pseudos