How to use the confuse.templates.String function in confuse

"""Convert a simple "shorthand" Python value to a `Template`.
    """
    if isinstance(value, Template):
        # If it's already a Template, pass it through.
        return value
    elif isinstance(value, abc.Mapping):
        # Dictionaries work as templates.
        return MappingTemplate(value)
    elif value is int:
        return Integer()
    elif isinstance(value, int):
        return Integer(value)
    elif isinstance(value, type) and issubclass(value, util.BASESTRING):
        return String()
    elif isinstance(value, util.BASESTRING):
        return String(value)
    elif isinstance(value, set):
        # convert to list to avoid hash related problems
        return Choice(list(value))
    elif (SUPPORTS_ENUM and isinstance(value, type)
            and issubclass(value, enum.Enum)):
        return Choice(value)
    elif isinstance(value, list):
        return OneOf(value)
    elif value is float:
        return Number()
    elif isinstance(value, float):
        return Number(value)
    elif value is None:
        return Template(None)
    elif value is REQUIRED:
        return Template()

def __init__(self, default=REQUIRED, pattern=None, expand_vars=False):
        """Create a template with the added optional `pattern` argument,
        a regular expression string that the value should match.
        """
        super(String, self).__init__(default)
        self.pattern = pattern
        self.expand_vars = expand_vars
        if pattern:
            self.regex = re.compile(pattern)

def as_template(value):
    """Convert a simple "shorthand" Python value to a `Template`.
    """
    if isinstance(value, Template):
        # If it's already a Template, pass it through.
        return value
    elif isinstance(value, abc.Mapping):
        # Dictionaries work as templates.
        return MappingTemplate(value)
    elif value is int:
        return Integer()
    elif isinstance(value, int):
        return Integer(value)
    elif isinstance(value, type) and issubclass(value, util.BASESTRING):
        return String()
    elif isinstance(value, util.BASESTRING):
        return String(value)
    elif isinstance(value, set):
        # convert to list to avoid hash related problems
        return Choice(list(value))
    elif (SUPPORTS_ENUM and isinstance(value, type)
            and issubclass(value, enum.Enum)):
        return Choice(value)
    elif isinstance(value, list):
        return OneOf(value)
    elif value is float:
        return Number()
    elif isinstance(value, float):
        return Number(value)
    elif value is None:
        return Template(None)

def as_str_expanded(self):
        """Get the value as a (Unicode) string, with env vars
        expanded by `os.path.expandvars()`.
        """
        return self.get(templates.String(expand_vars=True))

def as_str(self):
        """Get the value as a (Unicode) string. Equivalent to
        `get(unicode)` on Python 2 and `get(str)` on Python 3.
        """
        return self.get(templates.String())