Coupling SFG's

Description of issue:

SFG's should be able to be coupled together with other SFG's. The amount of in/output ports should be preserved when coupling.

Linked Requirements:

( 21 )

Potential Issues:

None

Blockers:

( #8 (closed), #12 (closed) )

Issue Requirements:

1. Given two or more SFG's then these SFG's should be able to be connected in any order if possible. This should return one SFG.
2. The amount of in/output ports should be preserved when coupling, that is do not modify the SFG's when coupling

Comment:

None