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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 install(packagename, save, save_dev, save_test, filename):
 """ Install the package via pip, pin the package only to requirements file. Use option to decide which file the package will be pinned to. """

    print('Installing ', packagename)
    print(sh_pip.install(packagename))
    if not filename:
        filename = get_filename(save, save_dev, save_test)
    try:
        add_requirements(packagename, filename)
    except AssertionError:
        print('Package already pinned in ', filename)