def user_data_dir(appname=None, appauthor=None, version=None, roaming=False):
    r"""Return full path to the user-specific data dir for this application.

        "appname" is the name of application.
            If None, just the system directory is returned.
        "appauthor" (only used on Windows) is the name of the
            appauthor or distributing body for this application. Typically
            it is the owning company name. This falls back to appname. You may
            pass False to disable it.
        "version" is an optional version path element to append to the
            path. You might want to use this if you want multiple versions
            of your app to be able to run independently. If used, this
            would typically be "<major>.<minor>".
            Only applied when appname is present.
        "roaming" (boolean, default False) can be set True to use the Windows
            roaming appdata directory. That means that for users on a Windows
            network setup for roaming profiles, this user data will be
            sync'd on login. See
            <http://technet.microsoft.com/en-us/library/cc766489(WS.10).aspx>
            for a discussion of issues.

    Typical user data directories are:
        Mac OS X:               ~/Library/Application Support/<AppName>  # or ~/.config/<AppName>, if the other does not exist
        Unix:                   ~/.local/share/<AppName>    # or in $XDG_DATA_HOME, if defined
        Win XP (not roaming):   C:\Documents and Settings\<username>\Application Data\<AppAuthor>\<AppName>
        Win XP (roaming):       C:\Documents and Settings\<username>\Local Settings\Application Data\<AppAuthor>\<AppName>
        Win 7  (not roaming):   C:\Users\<username>\AppData\Local\<AppAuthor>\<AppName>
        Win 7  (roaming):       C:\Users\<username>\AppData\Roaming\<AppAuthor>\<AppName>

    For Unix, we follow the XDG spec and support $XDG_DATA_HOME.
    That means, by default "~/.local/share/<AppName>".
    """
    if system == "win32":
        if appauthor is None:
            appauthor = appname
        const = roaming and "CSIDL_APPDATA" or "CSIDL_LOCAL_APPDATA"
        path = os.path.normpath(_get_win_folder(const))
        if appname:
            if appauthor is not False:
                path = os.path.join(path, appauthor, appname)
            else:
                path = os.path.join(path, appname)
    elif system == 'darwin':
        path = os.path.expanduser('~/Library/Application Support/')
        if appname:
            path = os.path.join(path, appname)
    else:
        path = os.getenv('XDG_DATA_HOME', os.path.expanduser("~/.local/share"))
        if appname:
            path = os.path.join(path, appname)
    if appname and version:
        path = os.path.join(path, version)
    return path
Return full path to the user-specific data dir for this application.

        "appname" is the name of application.
            If None, just the system directory is returned.
        "appauthor" (only used on Windows) is the name of the
            appauthor or distributing body for this application. Typically
            it is the owning company name. This falls back to appname. You may
            pass False to disable it.
        "version" is an optional version path element to append to the
            path. You might want to use this if you want multiple versions
            of your app to be able to run independently. If used, this
            would typically be "<major>.<minor>".
            Only applied when appname is present.
        "roaming" (boolean, default False) can be set True to use the Windows
            roaming appdata directory. That means that for users on a Windows
            network setup for roaming profiles, this user data will be
            sync'd on login. See
            <http://technet.microsoft.com/en-us/library/cc766489(WS.10).aspx>
            for a discussion of issues.

    Typical user data directories are:
        Mac OS X:               ~/Library/Application Support/<AppName>  # or ~/.config/<AppName>, if the other does not exist
        Unix:                   ~/.local/share/<AppName>    # or in $XDG_DATA_HOME, if defined
        Win XP (not roaming):   C:\Documents and Settings\<username>\Application Data\<AppAuthor>\<AppName>
        Win XP (roaming):       C:\Documents and Settings\<username>\Local Settings\Application Data\<AppAuthor>\<AppName>
        Win 7  (not roaming):   C:\Users\<username>\AppData\Local\<AppAuthor>\<AppName>
        Win 7  (roaming):       C:\Users\<username>\AppData\Roaming\<AppAuthor>\<AppName>

    For Unix, we follow the XDG spec and support $XDG_DATA_HOME.
    That means, by default "~/.local/share/<AppName>".
    
product/gradle-plugin/src/main/python/pip/_vendor/appdirs.py