import transformers
import pandas as pd

def preprocess_csv(file_url):
  """
  Downloads a CSV file from Hugging Face, preprocesses the data, and returns a single string.

  Args:
      file_url: URL of the CSV file on Hugging Face Hub.

  Returns:
      A string containing the preprocessed text from the CSV file.
  """
  # Download the file using transformers Hub
  file = transformers.file_download(file_url)

  # Read the CSV data using pandas
  df = pd.read_csv(file)

  # Preprocess the data (replace with your specific logic)
  # Example: Combine relevant columns into a single string
  text = " ".join(df["column1"].tolist() + df["column2"].tolist())

  return text