a template to declare an enum

[dwhall256]

Thank you both.

For my needs, I must be able to specify the enum values; so I created the 
sequence of `nnkEnumFieldDef` to give to `newEnum()` which involved copying 
leaves of the `Asgn` node.

For future me: `dumpTree` is your friend. For other learners, here is what I 
came up with. For current talent, I welcome suggestions for improvement.
    
    
    import std/macros
    
    macro declareEnum(enumName: untyped, enumPairsStmtList: untyped) =
      enumPairsStmtList.expectKind(nnkStmtList)
      var fields: seq[NimNode]
      for asgnNode in enumPairsStmtList:
        var node = newNimNode(nnkEnumFieldDef)
        node.add(asgnNode[0])
        node.add(asgnNode[1])
        fields.add(node)
      newEnum(enumName, fields, true, true)
    
    declareEnum(Foo):
      Alpha = 1
      Bravo = 2
      Charlie = 3
    
    proc main =
      let v: Foo = Alpha
      echo v
      echo Charlie.int
    
    when isMainModule:
      main()
    
    
    Run