code: def relevant_items(df):
      
      start_date = datetime(2013, 1, 1)
  
      df['DataProjeto'] = pd.to_datetime(df['DataProjeto'])
  
      # get only projects newer than start_date
      # and items with price > 0
      df = df[df.DataProjeto >= start_date]
      df = df[df.VlUnitarioAprovado > 0.0]
  
      return df
docs: Dataframe with items used by cultural projects,
      filtered by date and price.