--- a/env/lib/python3.7/site-packages/cachecontrol/heuristics.py	Thu May 14 16:47:39 2020 -0400
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,138 +0,0 @@
-import calendar
-import time
-
-from email.utils import formatdate, parsedate, parsedate_tz
-
-from datetime import datetime, timedelta
-
-TIME_FMT = "%a, %d %b %Y %H:%M:%S GMT"
-
-
-def expire_after(delta, date=None):
-    date = date or datetime.now()
-    return date + delta
-
-
-def datetime_to_header(dt):
-    return formatdate(calendar.timegm(dt.timetuple()))
-
-
-class BaseHeuristic(object):
-
-    def warning(self, response):
-        """
-        Return a valid 1xx warning header value describing the cache
-        adjustments.
-
-        The response is provided too allow warnings like 113
-        http://tools.ietf.org/html/rfc7234#section-5.5.4 where we need
-        to explicitly say response is over 24 hours old.
-        """
-        return '110 - "Response is Stale"'
-
-    def update_headers(self, response):
-        """Update the response headers with any new headers.
-
-        NOTE: This SHOULD always include some Warning header to
-              signify that the response was cached by the client, not
-              by way of the provided headers.
-        """
-        return {}
-
-    def apply(self, response):
-        updated_headers = self.update_headers(response)
-
-        if updated_headers:
-            response.headers.update(updated_headers)
-            warning_header_value = self.warning(response)
-            if warning_header_value is not None:
-                response.headers.update({'Warning': warning_header_value})
-
-        return response
-
-
-class OneDayCache(BaseHeuristic):
-    """
-    Cache the response by providing an expires 1 day in the
-    future.
-    """
-    def update_headers(self, response):
-        headers = {}
-
-        if 'expires' not in response.headers:
-            date = parsedate(response.headers['date'])
-            expires = expire_after(timedelta(days=1),
-                                   date=datetime(*date[:6]))
-            headers['expires'] = datetime_to_header(expires)
-            headers['cache-control'] = 'public'
-        return headers
-
-
-class ExpiresAfter(BaseHeuristic):
-    """
-    Cache **all** requests for a defined time period.
-    """
-
-    def __init__(self, **kw):
-        self.delta = timedelta(**kw)
-
-    def update_headers(self, response):
-        expires = expire_after(self.delta)
-        return {
-            'expires': datetime_to_header(expires),
-            'cache-control': 'public',
-        }
-
-    def warning(self, response):
-        tmpl = '110 - Automatically cached for %s. Response might be stale'
-        return tmpl % self.delta
-
-
-class LastModified(BaseHeuristic):
-    """
-    If there is no Expires header already, fall back on Last-Modified
-    using the heuristic from
-    http://tools.ietf.org/html/rfc7234#section-4.2.2
-    to calculate a reasonable value.
-
-    Firefox also does something like this per
-    https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching_FAQ
-    http://lxr.mozilla.org/mozilla-release/source/netwerk/protocol/http/nsHttpResponseHead.cpp#397
-    Unlike mozilla we limit this to 24-hr.
-    """
-    cacheable_by_default_statuses = set([
-        200, 203, 204, 206, 300, 301, 404, 405, 410, 414, 501
-    ])
-
-    def update_headers(self, resp):
-        headers = resp.headers
-
-        if 'expires' in headers:
-            return {}
-
-        if 'cache-control' in headers and headers['cache-control'] != 'public':
-            return {}
-
-        if resp.status not in self.cacheable_by_default_statuses:
-            return {}
-
-        if 'date' not in headers or 'last-modified' not in headers:
-            return {}
-
-        date = calendar.timegm(parsedate_tz(headers['date']))
-        last_modified = parsedate(headers['last-modified'])
-        if date is None or last_modified is None:
-            return {}
-
-        now = time.time()
-        current_age = max(0, now - date)
-        delta = date - calendar.timegm(last_modified)
-        freshness_lifetime = max(0, min(delta / 10, 24 * 3600))
-        if freshness_lifetime <= current_age:
-            return {}
-
-        expires = date + freshness_lifetime
-        return {'expires': time.strftime(TIME_FMT, time.gmtime(expires))}
-
-    def warning(self, resp):
-        return None