Why and how do we use the col() function to reference DataFrame columns as first-class objects?
col() creates a Column object enabling programmatic operations, method chaining, expressions, and type safety.
Writing robust, refactorable transformation pipelines that support method chaining and arithmetic.
from pyspark.sql.functions import col
df.select(col("order_id"), col("amount")).show()Practice typing production-grade PySpark code for Column Referencing with col().