code: def get_train_questions_only(df):
      train_questions_only_df = df[df["answered_correctly"] != -1]
      return train_questions_only_df
  
imports: import bigdl.orca.data.pandas
  from bigdl.orca.data.transformer import *
label_desc: Use image node_id 2 for calling a global function with example usage: get_train_questions_only(df) and returns: train_questions_only_df