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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 coerce(cls, key, value):
 """Convert plain dictionary to NestedMutable."""

        if value is None:
            return value
        if isinstance(value, cls):
            return value
        if isinstance(value, dict):
            return NestedMutableDict.coerce(key, value)
        if isinstance(value, list):
            return NestedMutableList.coerce(key, value)
        return super(cls).coerce(key, value)