diff --git a/c_.nix b/c_.nix
index 8e787e9..04f23fa 100644
--- a/c_.nix
+++ b/c_.nix
@@ -1,100 +1,111 @@
 # a small helper that only builds on top of builtins functions
-{src}@inputs:
-builtins // (let 
-formatSecondsSinceEpoch = t:
-let
-rem = x: y: x - x / y * y;
-days = t / 86400;
-secondsInDay = rem t 86400;
-hours = secondsInDay / 3600;
-minutes = (rem secondsInDay 3600) / 60;
-seconds = rem t 60;
+{ src }@inputs:
+builtins // (
+  let
+    formatSecondsSinceEpoch = t:
+      let
+        rem = x: y: x - x / y * y;
+        days = t / 86400;
+        secondsInDay = rem t 86400;
+        hours = secondsInDay / 3600;
+        minutes = (rem secondsInDay 3600) / 60;
+        seconds = rem t 60;
 
-# Courtesy of https://stackoverflow.com/a/32158604.
-z = days + 719468;
-era = (if z >= 0 then z else z - 146096) / 146097;
-doe = z - era * 146097;
-yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365;
-y = yoe + era * 400;
-doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
-mp = (5 * doy + 2) / 153;
-d = doy - (153 * mp + 2) / 5 + 1;
-m = mp + (if mp < 10 then 3 else -9);
-y' = y + (if m <= 2 then 1 else 0);
+        # Courtesy of https://stackoverflow.com/a/32158604.
+        z = days + 719468;
+        era = (if z >= 0 then z else z - 146096) / 146097;
+        doe = z - era * 146097;
+        yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365;
+        y = yoe + era * 400;
+        doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
+        mp = (5 * doy + 2) / 153;
+        d = doy - (153 * mp + 2) / 5 + 1;
+        m = mp + (if mp < 10 then 3 else -9);
+        y' = y + (if m <= 2 then 1 else 0);
 
-pad = s: if builtins.stringLength s < 2 then "0" + s else s;
-in "${toString y'}${pad (toString m)}${pad (toString d)}${pad (toString hours)}"
-+ "${pad (toString minutes)}${pad (toString seconds)}";
+        pad = s: if builtins.stringLength s < 2 then "0" + s else s;
+      in
+      "${toString y'}${pad (toString m)}${pad (toString d)}${pad (toString hours)}"
+      + "${pad (toString minutes)}${pad (toString seconds)}";
 
-fetchTree =
-# this is the value of flake.lock#lock.nodes.${input_name}.locked
-{type
-, host? ""
-, owner? ""
-, repo? ""
-, rev? ""
-, submodules? ""
-, path? ""
-, narHash? null
-, lastModified? 0
-}@info:
-if info.type == "github" then
-{ outPath =
-  fetchTarball
-    ({ url = "https://api.${info.host or "github.com"}/repos/"
-     + "${info.owner}/${info.repo}/tarball/${info.rev}"; }
-     // (if info ? narHash then { sha256 = info.narHash; } else {})
-    );
-  rev = info.rev;
-  shortRev = builtins.substring 0 7 info.rev;
-  lastModified = info.lastModified;
-  lastModifiedDate = formatSecondsSinceEpoch info.lastModified;
-  narHash = info.narHash;
-}
-else if info.type == "git" then
-{ outPath =
-  builtins.fetchGit
-    ({ url = info.url; }
-     // (if info ? rev then { inherit (info) rev; } else {})
-     // (if info ? ref then { inherit (info) ref; } else {})
-     // (if info ? submodules then { inherit (info) submodules; } else {})
-    );
-  lastModified = info.lastModified;
-  lastModifiedDate = formatSecondsSinceEpoch info.lastModified;
-  narHash = info.narHash;
-} // (if info ? rev then {
-rev = info.rev;
-shortRev = builtins.substring 0 7 info.rev;
-} else {
-})
-else if info.type == "path" then
-{ outPath = builtins.path { 
-  path = if builtins.substring 0 1 info.path != "/"
-    then src + ("/" + info.path)  # make this absolute path by prepending ./
-    else info.path; # it's already an absolute path
-                          };
-narHash = info.narHash;
-}
-else if info.type == "tarball" then
-{ outPath =
-  fetchTarball
-    ({ inherit (info) url; }
-     // (if info ? narHash then { sha256 = info.narHash; } else {})
-    );
-}
-else if info.type == "gitlab" then
-{ inherit (info) rev narHash lastModified;
-  outPath =
-    fetchTarball
-    ({ url = "https://${info.host or "gitlab.com"}/api/v4/projects/${info.owner}%2F${info.repo}/repository/archive.tar.gz?sha=${info.rev}"; }
-     // (if info ? narHash then { sha256 = info.narHash; } else {})
-    );
-  shortRev = builtins.substring 0 7 info.rev;
-}
-else
-# FIXME: add Mercurial, tarball inputs.
-throw "flake input has unsupported input type '${info.type}'";
-in {
-  inherit fetchTree;
-})
+    fetchTree =
+      # this is the value of flake.lock#lock.nodes.${input_name}.locked
+      { type
+      , host ? ""
+      , owner ? ""
+      , repo ? ""
+      , rev ? ""
+      , submodules ? ""
+      , path ? ""
+      , narHash ? null
+      , lastModified ? 0
+      }@info:
+      if info.type == "github" then
+        {
+          outPath =
+            fetchTarball
+              ({
+                url = "https://api.${info.host or "github.com"}/repos/"
+                + "${info.owner}/${info.repo}/tarball/${info.rev}";
+              }
+              // (if info ? narHash then { sha256 = info.narHash; } else { })
+              );
+          rev = info.rev;
+          shortRev = builtins.substring 0 7 info.rev;
+          lastModified = info.lastModified;
+          lastModifiedDate = formatSecondsSinceEpoch info.lastModified;
+          narHash = info.narHash;
+        }
+      else if info.type == "git" then
+        {
+          outPath =
+            builtins.fetchGit
+              ({ url = info.url; }
+              // (if info ? rev then { inherit (info) rev; } else { })
+              // (if info ? ref then { inherit (info) ref; } else { })
+              // (if info ? submodules then { inherit (info) submodules; } else { })
+              );
+          lastModified = info.lastModified;
+          lastModifiedDate = formatSecondsSinceEpoch info.lastModified;
+          narHash = info.narHash;
+        } // (if info ? rev then {
+          rev = info.rev;
+          shortRev = builtins.substring 0 7 info.rev;
+        } else { })
+      else if info.type == "path" then
+        {
+          outPath = builtins.path {
+            path =
+              if builtins.substring 0 1 info.path != "/"
+              then src + ("/" + info.path)  # make this absolute path by prepending ./
+              else info.path; # it's already an absolute path
+          };
+          narHash = info.narHash;
+        }
+      else if info.type == "tarball" then
+        {
+          outPath =
+            fetchTarball
+              ({ inherit (info) url; }
+              // (if info ? narHash then { sha256 = info.narHash; } else { })
+              );
+        }
+      else if info.type == "gitlab" then
+        {
+          inherit (info) rev narHash lastModified;
+          outPath =
+            fetchTarball
+              ({ url = "https://${info.host or "gitlab.com"}/api/v4/projects/${info.owner}%2F${info.repo}/repository/archive.tar.gz?sha=${info.rev}"; }
+              // (if info ? narHash then { sha256 = info.narHash; } else { })
+              );
+          shortRev = builtins.substring 0 7 info.rev;
+        }
+      else
+      # FIXME: add Mercurial, tarball inputs.
+        throw "flake input has unsupported input type '${info.type}'";
+  in
+  {
+    inherit fetchTree;
+  }
+)