Association Lists

lAn association list is a list of pairs.
[[ÒJanuaryÓ, 31], [ÒFebruaryÓ, 28], [ÒMarchÓ, 31], [ÒAprilÓ, 30]]
lTypically all first elements of the pairs are of the same type, and all second elements are of the same type.
lThe pairs are not necessarily of the same type as each other.