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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def is_valid_command(self, word: str) -> Tuple[bool, str]: """Determine whether a word is a valid name for a command. Commands can not include redirection characters, whitespace, or termination characters. They also cannot start with a shortcut. If word is not a valid command, return False and error text This string is suitable for inclusion in an error message of your choice: valid, errmsg = statement_parser.is_valid_command('>') if not valid: errmsg = "Alias {}".format(errmsg) """

        valid = False

        if not word:
            return False, 'cannot be an empty string'

        if word.startswith(constants.COMMENT_CHAR):
            return False, 'cannot start with the comment character'

        for (shortcut, _) in self.shortcuts:
            if word.startswith(shortcut):
                # Build an error string with all shortcuts listed
                errmsg = 'cannot start with a shortcut: '
                errmsg += ', '.join(shortcut for (shortcut, _) in self.shortcuts)
                return False, errmsg

        errmsg = 'cannot contain: whitespace, quotes, '
        errchars = []
        errchars.extend(constants.REDIRECTION_CHARS)
        errchars.extend(self.terminators)
        errmsg += ', '.join([shlex.quote(x) for x in errchars])

        match = self._command_pattern.search(word)
        if match:
            if word == match.group(1):
                valid = True
                errmsg = ''
        return valid, errmsg