def _get_indent_num_from_line(*, line: str) -> int:
    """
    Get an indent number from a specified docstring line.

    Parameters
    ----------
    line : str
        Target docstring line.

    Returns
    -------
    indent_num : int
        Indent number of a specified docstring line.
    """
    spaces: int = 0
    for char in line:
        if char != ' ':
            break
        spaces += 1
    indent_num: int = spaces // 4
    return indent_num