Outline a complet mechanistic sequence for the reaction of 2-bromoheptane with potassium 2-methyl-2-propoxide in 2-methyly-2-propanol solvent to form the three alkenes generated in the reaction (1-heptene, tras-2-heptene, and cis-2-heptene). Include a clear drawing of the anti-periplanar transition state for the formation of each alkene.