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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 getPathOfExecutable(executable):
 """ Returns the full path of the executable, or None if the executable can not be found. """

    exe_paths = os.environ['PATH'].split(':')
    for exe_path in exe_paths:
        exe_file = os.path.join(exe_path, executable)
        if os.path.isfile(exe_file) and os.access(exe_file, os.X_OK):
            return exe_file
    return None