code: public NumberExpression<T> ceil() {
          if (ceil == null) {
              ceil = Expressions.numberOperation(getType(), MathOps.CEIL, mixin);
          }
          return ceil;
      }
docs: Create a {@code ceil(this)} expression
  
  <p>Returns the smallest (closest to negative infinity)
  {@code double} value that is greater than or equal to the
  argument and is equal to a mathematical integer</p>
  
  @return ceil(this)
  @see java.lang.Math#ceil(double)