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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 get_version(exe_path='youtube-dl'):
    '''Get the version string of youtube-dl.'''
    process = subprocess.Popen(
        [exe_path, '--version'],
        stdout=subprocess.PIPE
    )
    version_string = process.communicate()[0]
    version_string = version_string.decode().strip()

    assert ' ' not in version_string, version_string

    return version_string