Append integer to beginning of list in Python

I have an integer and a list. I would like to make a new list of them beginning with the variable and ending with the list. Writing a + list I get errors. The compiler handles a as integer, thus I cannot use append, or extend either. How would you do this?

    >>> a = 5
    >>> li = [1, 2, 3]
    >>> [a] + li  # Don't use 'list' as variable name.
    [5, 1, 2, 3]