def decorate(string, decoration='=', n1=10, n2=None):
    """
    Decorate a string to emphasise it

    Args:
        :string: string to decorate
        :decoration: string used
        :n1: prefix multiplier
        :n2: suffix multiplier

    Returns:
        :mod_string: modified string
    """
    if not isinstance(string, str):
        raise TypeError("'string' must be of type str")
    if not isinstance(decoration, str):
        raise TypeError("'decoration' must be of type str")
    if not isinstance(n1, int):
        raise TypeError("'n1' must be of type int")
    if n2 is None:
        n2 = n1
    mod_string = decoration * n1 + ' ' + string + ' ' + decoration * n2
    return mod_string
