fix doc

Author: adriangb

datafusion/physical-optimizer/src/simplify_expressions/unwrap_cast.rs

@@ -30,22 +30,6 @@
 //!
 //! Physical expression: `cast(column as INT64) > INT64(10)`
 //! Optimized to: `column > INT32(10)` (assuming column is INT32)
-//!
-//! # Usage
-//!
-//! ```rust
-//! use datafusion_physical_optimizer::simplify_expressions::PhysicalExprSimplifier;
-//! use arrow::datatypes::Schema;
-//! use std::sync::Arc;
-//! use datafusion_physical_plan::PhysicalExpr;
-//!
-//! // Apply unwrap cast optimization to a physical expression
-//! fn optimize_expression(expr: Arc<dyn PhysicalExpr>, schema: &Schema) -> datafusion_common::Result<Arc<dyn PhysicalExpr>> {
-//!     let simplifier = PhysicalExprSimplifier::new(schema);
-//!     let result = simplifier.unwrap_casts(expr)?;
-//!     Ok(result.data)
-//! }
-//! ```
 
 use arrow::datatypes::{DataType, Schema};
 use datafusion_common::{
@@ -59,7 +43,7 @@ use datafusion_physical_plan::PhysicalExpr;
 use std::sync::Arc;
 
 /// Attempts to unwrap casts in comparison expressions.
-pub fn unwrap_cast_in_comparison(
+pub(crate) fn unwrap_cast_in_comparison(
     expr: Arc<dyn PhysicalExpr>,
     schema: &Schema,
 ) -> Result<Transformed<Arc<dyn PhysicalExpr>>> {