diff --git a/src/core/mod.rs b/src/core/mod.rs
new file mode 100644
index 0000000..ea62ab0
--- /dev/null
+++ b/src/core/mod.rs
@@ -0,0 +1,3 @@
+pub mod df;
+pub mod xseries;
+pub mod dateseries;
\ No newline at end of file