time interal condition and sessions in range changed

[krishdotn1]

function convert_interval(self, time_interval) suppose time_interval is 1d it will raise an error "wrong time_interval" So I have fixed it might be lower case r upper case and when I download VIXY data then time_interval="1d" so it raise error.

session_in_range variable takes Date type and it is my Date

when we use tz=pytz.UTC it raise error of timezone so it will be better to use df = nyse.sessions_in_range( pd.Timestamp(start), pd.Timestamp(end) )

or

`df = nyse.sessions_in_range( start, end ) ' because Date takes both pd.Timestamps and str

[zhumingpassional]

thanks