def indent(lines, amount=2, char=' '):
    r"""Indent a string.

    Prepends whitespace to every line in the passed string. (Lines are
    separated by newline characters.)

    Args:
        lines (str): The string to indent.

    Keyword Args:
        amount (int): The number of columns to indent by.
        char (str): The character to to use as the indentation.

    Returns:
        str: The indented string.

    Example:
        >>> print(indent('line1\nline2', char='*'))
        **line1
        **line2
    """
    lines = str(lines)
    padding = amount * char
    return padding + ('\n' + padding).join(lines.split('\n'))