 VariableExprAST::Codegen = ->
   # Look this variable up in the function.
   V = NamedValues[@name]
-  if V == 0 then throw new Error("Unknown variable name")
+  if not V then throw new Error("Unknown variable name")
 
   # Load the value.
   return Builder.createLoad(V, @name)

  OperandV = @operand.Codegen()
  if not OperandV then return null
  
  F = TheModule.getFunction("unary"+@Opcode)
  if not F
    throw new Error("Unknown unary operator")
  
  return Builder.CreateCall(F, OperandV, "unop")

BinaryExprAST::Codegen = ->
  # Special case '=' because we don't want to emit the LHS as an expression.

    else
      EOF

  testchar: ->
    if @buffer.length
      @buffer[0]
    else
      EOF

  # gettok - Return the next token from standard input.
  gettok: ->
