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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 find_program (program):
 """Look for program in environment PATH variable."""

    if os.name == 'nt':
        # Add some well-known archiver programs to the search path
        path = os.environ['PATH']
        path = append_to_path(path, get_nt_7z_dir())
        path = append_to_path(path, get_nt_mac_dir())
        path = append_to_path(path, get_nt_winrar_dir())
    else:
        # use default path
        path = None
    return which(program, path=path)