Question

In to kill a mockingbird, "Summer was on the way; Jem and I awaited it with impatience. Summer was our best season: It was sleeping on the back screened porch in cots, or trying to sleep in the treehouse; summer was everything good to eat; It was a thousand colors in a parched landscape; but most of all, summer was Dill."(Lee 38)
explain the function of the first semicolon