title: TypeError: 'Column' object is not callable Pysarpk, when joining two tables
body: <p>so i am trying to 2 join 2 data frames and in doing so i am getting the following error.</p>
  
  <blockquote>
    <p>TypeError: 'Column' object is not callable</p>
  </blockquote>
  
  <p>I am loading data as simple csv files, following is the schema loaded from CSVs.</p>
  
  <blockquote>
    <p>root
     |-- movie_id,title: string (nullable = true)</p>
    
    <p>root
     |-- user_id,movie_id,tag,timestamp: string (nullable = true)</p>
  </blockquote>
  
  <p>following is my implementation for loading </p>
  
  <pre><code>df1 = spark.read.format("csv").option("header", "true").load("collaborative/titles.csv", header=True, sep="|")
  df2 = spark.read.format("csv").option("header", "true").load("collaborative/tags.csv", header=True, sep="|")
  df1.printSchema()
  df2.printSchema()
  df1.alias("df1").join(df2.alias("df2"), col("df1.movie_id").equalTo(col("df2.movie_id"))).select(col("df2.*"))
  </code></pre>