anchor.diff:  
   type Compilation {
     compiler: Compiler!
  -  contracts: [Contract!]
     sources: [Source]!
  +  contracts: [SourceContract]!
   }
   
   type Compiler {
  
positive.code: # stub
  type AbiItem {
    type: String
  }
  
  type Network {
  
negative.code: scalar Value
  scalar Bytes
  scalar Object
  scalar ByteOffset
  scalar FileIndex
  
  