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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 is_nullable_list(val, vtype):
 """Return True if list contains either values of type `vtype` or None."""

    return (isinstance(val, list) and
            any(isinstance(v, vtype) for v in val) and
            all((isinstance(v, vtype) or v is None) for v in val))