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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def bddvar(name, index=None):
 r"""Return a unique BDD variable. A Boolean *variable* is an abstract numerical quantity that may assume any value in the set :math:`B = \{0, 1\}`. The ``bddvar`` function returns a unique Boolean variable instance represented by a binary decision diagram. Variable instances may be used to symbolically construct larger BDDs. A variable is defined by one or more *names*, and zero or more *indices*. Multiple names establish hierarchical namespaces, and multiple indices group several related variables. If the ``name`` parameter is a single ``str``, it will be converted to ``(name, )``. The ``index`` parameter is optional; when empty, it will be converted to an empty tuple ``()``. If the ``index`` parameter is a single ``int``, it will be converted to ``(index, )``. Given identical names and indices, the ``bddvar`` function will always return the same variable: True To create several single-letter variables: To create variables with multiple names (inner-most first):
 .. seealso:: For creating arrays of variables with incremental indices, use the :func:`pyeda.boolalg.bfarray.bddvars` function. """

    bvar = boolfunc.var(name, index)
    try:
        var = _VARS[bvar.uniqid]
    except KeyError:
        var = _VARS[bvar.uniqid] = BDDVariable(bvar)
        _BDDS[var.node] = var
    return var