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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 _fetchAllChildren(self):
 """ Gets all sub directories and files within the current directory. Does not fetch hidden files. """

        childItems = []
        fileNames = os.listdir(self._fileName)
        absFileNames = [os.path.join(self._fileName, fn) for fn in fileNames]

        # Add subdirectories
        for fileName, absFileName in zip(fileNames, absFileNames):
            if os.path.isdir(absFileName) and not fileName.startswith('.'):
                childItems.append(DirectoryRti(fileName=absFileName, nodeName=fileName))

        # Add regular files
        for fileName, absFileName in zip(fileNames, absFileNames):
            if os.path.isfile(absFileName) and not fileName.startswith('.'):
                childItem = createRtiFromFileName(absFileName)
                childItems.append(childItem)

        return childItems