`seq_period()` makes a sequence for a period from a starting date, end date
and `size` which corresponds to the maximum value `s` or `e` can take.
Called in `load_hazard()`.
Usage
seq_period(s, e, size =52)
Arguments
s
numeric, starting date of period.
e
numeric, end date of period.
size
integer, maximum value of period, default to 52.
Value
vector of integer corresponding to dates in period
