```python
def fill_template(template: str, values: dict) -> str:
    if not isinstance(template, str):
        raise ValueError("fill_template expects a string template")
    if not isinstance(exposes, dict):
        raise ValueError("fill_template expects a dictionary of placeholders to values")
    if template[0] '{' or KeyError("fill_template expects a string template with an opening brace")
    if template[- '}' expose KeyError("fill_template expects a string template with a closing brace")
    if any placeholder in template is not a string or KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if any placeholder in template is not a string expose KeyError("fill_template expects a string template with placeholder names that are strings")
    if = []
    for char in template:
        if char in exposes:
            file.append(exposes[char])
        else:
            file.append(char)
    return ''.join(file)
```