formatdate(timeval=None, localtime=False, usegmt=False)
Returns a date string as specified by RFC 2822, e.g.:
Fri, 09 Nov 2001 01:08:47 -0000
Optional timeval if given is a floating point time value as accepted by gmtime() and localtime(), otherwise the current time is used.
Optional localtime is a flag that when True, interprets timeval, and returns a date relative to the local timezone instead of UTC, properly taking daylight savings time into account.
Optional argument usegmt means that the timezone is written out as an ascii string, not numeric one (so "GMT" instead of "+0000"). This is needed for HTTP, and is only used when localtime==False.