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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_one(schema=str):
 """Expect the input sequence to contain a single value. :keyword schema: Custom schema to apply to the input value. Defaults to just string, since this is designed for query params. """

    def validate(val):
        """Unpack a single item from the inputs sequence and run validation.

        NOTE(larsbutler): This code is highly opinionated for bottle, since
        bottle query params are wrapped in a list, even if there is just a
        single value for a given parameter.
        """
        [value] = val
        return volup.Coerce(schema)(value)
    return validate