code: def preprocess_df(df):
      """Preprocesses the dataframe.
  
          - Remove all rows with missing values in the following columns:
              - Consumer complaint narrative
              - Issue
              - Product
  
      Args:
          df (pd.DataFrame): The dataframe to preprocess.
  
      Returns:
          pd.DataFrame: The preprocessed dataframe.
      """
      return df.dropna(
          subset=["Consumer complaint narrative", "Issue", "Product"]
      )
  
imports: import pandas
  from ludwig.datasets.loaders.dataset_loader import DatasetLoader
label_desc: Use image node_id 1 for calling a global function with example usage: preprocess_df(df) and returns: df