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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 env(*_vars, **kwargs):
 """Search for the first defined of possibly many env vars. Returns the first environment variable defined in vars, or returns the default defined in kwargs. """

    for v in _vars:
        value = os.environ.get(v, None)
        if value:
            return value
    return kwargs.get('default', '')