from typing import Optional


def render_dot_link(source: str, dest: str, label: Optional[str]) -> str:
    """Render a link between a `source` and a `dest` in a dot file.

    Parameters
    ----------
    source : str
        The source of the link in the dot file
    dest : str
        The destination of the link in the dot file
    label : Optional[str]
        If set, will be the label of the link.

    Returns
    -------
    str
        The line representing the link for the dot file.

    """
    result = f"{source} -> {dest}"
    if label:
        result += f' [label="{label}"]'
    return result