A construction company has many branches spread all over the country. The company has two types of constructions to offer : Housing and Commercial. The housing company provides low income housing, medium style housing and high end housing schemes, while on the commercial side it offers multiplexes and shopping zones. The customers of the company may be individuals or corporate clients. Draw the ER diagram for the company showing generalization or specialization hierarchies and aggregations, if any. Also create 3NF tables of your design.