Add doc

pred/doc.go

@@ -0,0 +1,24 @@
+/*
+Package pred provides predicates for basic logic operations.
+
+Predicates with conditional jobs like run.If allows to make non-linear
+flow. In terms of floc predicate should return true or false depending
+on context.
+
+  const idReadyFlag = 100
+
+  testReady := func(ctx floc.Context) bool {
+	if flag := ctx.Value(idReadyFlag); flag != nil {
+      return flag.(bool)
+	}
+
+    return false
+  }
+
+  flow := run.Sequence(
+    ..., // Some job done here
+    job.If(testReady, job.Background(writeToDisk)), // Write some data ready to disk in background
+    ..., // Some job more
+  )
+*/
+package pred