def insert(self, i, *exprs):
self._assert_supports_contents()<EOL>for j, expr in enumerate(exprs):<EOL><INDENT>self._contents.insert(i + j, expr)<EOL><DEDENT>
Insert content at specified position into expression.

        :param int i: Position to add content to
        :param Union[TexExpr,str] exprs: List of contents to add

        >>> expr = TexExpr('textbf', ('hello',))
        >>> expr
        TexExpr('textbf', ['hello'])
        >>> expr.insert(0, 'world')
        >>> expr
        TexExpr('textbf', ['world', 'hello'])