ot None, the UTC offset is also attached, giving
giving a full format of 'YYYY-MM-DD HH:MM:SS.mmmmmm+HH:MM'.

Optional argument sep specifies the separator between date and
time, default 'T'.

The optional argument timespec specifies the number of additional
terms of the time to include. Valid options are 'auto', 'hours',
'minutes', 'seconds', 'milliseconds' and 'microseconds'.
z