bidirectional map

[ryu-bu]

Describe the bug
bidirectional map is not supported.

To Reproduce
Steps to reproduce the behavior:

1. MAP function is not bidirectional

Expected behavior
MAP function should be bidirectional, so it can direct and get directed by one block without requiring extra blocks.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.

[rkrishnasanka]

@ryu-bu can you put the lfr file here? I want to take a look at how this would change the language spec