Reverting some changes after code review

sql/core/src/main/scala/org/apache/spark/sql/functions.scala

@@ -1099,6 +1099,14 @@ object functions {
    */
   def input_file_name(): Column = withExpr { InputFileName() }
 
+  /**
+   * Return true iff the column is NaN.
+   *
+   * @group normal_funcs
+   * @since 1.6.0
+   */
+  def isnan(e: Column): Column = withExpr { IsNaN(e.expr) }
+
   /**
    * Return true iff the column is null.
    *
@@ -1148,6 +1156,16 @@ object functions {
    */
   def monotonically_increasing_id(): Column = withExpr { MonotonicallyIncreasingID() }
 
+  /**
+   * Returns col1 if it is not NaN, or col2 if col1 is NaN.
+   *
+   * Both inputs should be floating point columns (DoubleType or FloatType).
+   *
+   * @group normal_funcs
+   * @since 1.5.0
+   */
+  def nanvl(col1: Column, col2: Column): Column = withExpr { NaNvl(col1.expr, col2.expr) }
+
   /**
    * Unary minus, i.e. negate the expression.
    * {{{
@@ -1298,6 +1316,14 @@ object functions {
     CaseWhen(Seq((condition.expr, lit(value).expr)))
   }
 
+  /**
+   * Computes bitwise NOT (~) of a number.
+   *
+   * @group normal_funcs
+   * @since 1.4.0
+   */
+  def bitwiseNOT(e: Column): Column = withExpr { BitwiseNot(e.expr) }
+
   /**
    * Parses the expression string into the column that it represents, similar to
    * [[Dataset#selectExpr]].
@@ -1506,14 +1532,6 @@ object functions {
    */
   def bin(columnName: String): Column = bin(Column(columnName))
 
-  /**
-   * Computes bitwise NOT (~) of a number.
-   *
-   * @group math_funcs
-   * @since 1.4.0
-   */
-  def bitwiseNOT(e: Column): Column = withExpr { BitwiseNot(e.expr) }
-
   /**
    * Computes the cube-root of the given value.
    *
@@ -1678,26 +1696,6 @@ object functions {
    */
   def hex(column: Column): Column = withExpr { Hex(column.expr) }
 
-  /**
-   * Return true iff the column is NaN.
-   *
-   * Both inputs should be floating point columns (DoubleType or FloatType).
-   *
-   * @group math_funcs
-   * @since 1.6.0
-   */
-  def isnan(e: Column): Column = withExpr { IsNaN(e.expr) }
-
-  /**
-   * Returns col1 if it is not NaN, or col2 if col1 is NaN.
-   *
-   * Both inputs should be floating point columns (DoubleType or FloatType).
-   *
-   * @group math_funcs
-   * @since 1.5.0
-   */
-  def nanvl(col1: Column, col2: Column): Column = withExpr { NaNvl(col1.expr, col2.expr) }
-
   /**
    * Inverse of hex. Interprets each pair of characters as a hexadecimal number
    * and converts to the byte representation of number.