<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_paths(scheme=_get_default_scheme(), vars=None, expand=True):
 """Return a mapping containing an install scheme. ``scheme`` is the install scheme name. If not provided, it will return the default scheme for the current platform. """

    _ensure_cfg_read()
    if expand:
        return _expand_vars(scheme, vars)
    else:
        return dict(_SCHEMES.items(scheme))