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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 sheetDelete(book=None,sheet=None):
 """ Delete a sheet from a book. If either isn't given, use the active one. """

    if book is None:
        book=activeBook()
    if sheet in sheetNames():
        PyOrigin.WorksheetPages(book).Layers(sheetNames().index(sheet)).Destroy()