from datetime import datetime as DateTime
from string.templatelib import Template, Interpolation
from html import escape as html_escape


def html(template: Template) -> str:
    if not isinstance(template, Template):
        raise TypeError("Normal Strings are not allowed. Use a template string")

    parts = []

    for item in template:
        match item:
            case Interpolation():
                parts.append(html_escape(str(item.value)))
            case str():
                parts.append(item)

    return "".join(parts)

world = "<b>world</b>"
dt = DateTime.now()
print(html(t"Hello {world}. {dt}"))

try:
    html(f"Wrong {world}")
except TypeError as e:
    print(e)