'Returns a DatetimeIndex representing all the minutes in this calendar.'

@lazyval
def all_minutes(self):

    opens_in_ns = self._opens.values.astype('datetime64[ns]')
    closes_in_ns = self._closes.values.astype('datetime64[ns]')
    deltas = (closes_in_ns - opens_in_ns)
    daily_sizes = ((deltas / NANOS_IN_MINUTE) + 1)
    num_minutes = np.sum(daily_sizes).astype(np.int64)
    all_minutes = np.empty(num_minutes, dtype='datetime64[ns]')
    idx = 0
    for (day_idx, size) in enumerate(daily_sizes):
        size_int = int(size)
        all_minutes[idx:(idx + size_int)] = np.arange(opens_in_ns[day_idx], (closes_in_ns[day_idx] + NANOS_IN_MINUTE), NANOS_IN_MINUTE)
        idx += size_int
    return DatetimeIndex(all_minutes).tz_localize('UTC')
