# Functions
Between returns true if t is between a and b inclusive.
Ceil returns the result of rounding t up to a multiple of d (since the zero time).
IsMultiple returns true if t is some multiple of d (since the zero time).
MustParseISO8601D is like ParseISO8601D, but panics if there's an error.
NewRoundedTicker returns a new RoundedTicker.
Next returns the nearest multiple of d after t (since the zero time).
ParseISO8601D parses an ISO 8601 duration string.
Prev returns the nearest multiple of d before t (since the zero time).
# Variables
ErrInt64Overflow is returned by ParseISO8601D if the duration can't fit in an int64.
# Structs
RoundedTicker is like a time.Ticker, but rounded up to the nearest multiple of the tick Duration from the zero time.