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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 none_coalesce_handle(tokens):
 """Process the None-coalescing operator."""

    if len(tokens) == 1:
        return tokens[0]
    elif tokens[0].isalnum():
        return "({b} if {a} is None else {a})".format(
            a=tokens[0],
            b=none_coalesce_handle(tokens[1:]),
        )
    else:
        return "(lambda {x}: {b} if {x} is None else {x})({a})".format(
            x=none_coalesce_var,
            a=tokens[0],
            b=none_coalesce_handle(tokens[1:]),
        )