Patrick Learned how to Fork.

TODO 
   Change parser to use <> syntax (and update all tests) (patrick)
   Think about on-reset, add it
   Think about expanding mems, more complicated than first glance! Change DefMem to be size, and element type
   Think about max(op1,op2) for muxes.
   Make instances always male, flip the bundles on declaration
   Talk to palmer/patrick about how writing passes is going to be supported
   Add asserts, printf to spec
   Write lowering step for primops
   Figure out how widths propogate for all updated primops (Adam)
   Add bit-reduce-and etc to primops (Jonathan)
   //HANDLED IN FRONT END// Write pass to rename identifiers (alpha-transform) (Adam)
   Add partial bulk connect (Scott, Stephen)
   Add FIFOs to the IR (Palmer)
   Multi-streams for print statements/asserts (Jack)
   Consider def female node. (Patrick) 
   Think about supporting generic primops on bundles and vecs (Adam) (wait until front-end more completed)

   Update spec
      add assertions
      cannot connect directly to a mem (loc can never contain a mem)
      Front-end needs to guarantee unique names per module.
      FIRRTL rule: No name can be a prefix of any other name.
   Future questions to address in spec:
      Introduction – motivation, and intended usage
      Philosophical justifications for all constructs
      More introduction for types, e.g. what is a ground type?
      What is a statement? What is an expression? What is a memory? Difference between vector type and memory? What are accessors for?
      Why would I ever write an empty statement? Mainly for use by compiler/passes
      What is a structural element? Duplication?
      Subtracting two unsigned numbers… Should talk to a math guy to figure it out
      What are shift left and shift right operations? HW doesn’t have these concepts. Need justification.
      What is lowered form? What is it for?


Checks:
   Subfields are only on bundles, before type inference 
   After adding dynamic assertions, insert bounds check with accessor expansion
   All things only assigned to once
   Front-end needs to guarantee unique names per module.
   FIRRTL rule: No name can be a prefix of any other name.

Tests:
   Error if declare anything other than module in circuit
   Error if incorrectly assign stuff, like use = instead of :=
   Error: Node not parsed for stmts

Male node:
defnode n = e
==>
wire n
n := e

Female node:
defnode n = e
==>
wire n 
e := n