anchor.diff:                 (currentStep:ResolverStep)
                   groupName
                  (currentRequirement:PackageRequirement)
  -               (getVersionsF: PackageSource list -> ResolverStrategy -> GroupName -> PackageName -> Async<seq<SemVerInfo * PackageSource list>>)
  +               (getVersionsF: PackageSource list -> ResolverStrategy -> GroupName -> PackageName -> seq<SemVerInfo * PackageSource list>)
                   globalOverride
                   globalStrategyForDirectDependencies
                   globalStrategyForTransitives        =
  
positive.code:             | Specific v -> getSingleVersion v
              | _ ->
                  let resolverStrategy = getResolverStrategy globalStrategyForDirectDependencies globalStrategyForTransitives allRequirementsOfCurrentPackage currentRequirement
                  let result =
                      getVersionsF currentRequirement.Sources resolverStrategy groupName currentRequirement.Name
                      |> Async.RunSynchronously
                  result
  
          let compatibleVersions = Seq.filter (isInRange id) (availableVersions)
          let compatibleVersions, globalOverride =
  
negative.code:     }
  
  
  let private explorePackageConfig getPackageDetailsBlock (pkgConfig:PackageConfig) =
      let dependency, version = pkgConfig.Dependency, pkgConfig.Version
      let packageSources      = pkgConfig.Sources
  
  