1. A method of using a computer program that accesses legacy program code comprising: distinguishing between non-legacy program code of the computer program and legacy program code of the computer program; separating the computer program into at least a first logical unit comprising non-legacy program code and at least a second logical unit comprising legacy program code; including interface code within the first logical unit, wherein the interface code is non-legacy program code that communicates with the second logical unit; and outputting the first logical unit and the second logical unit.